Structure-based design and synthesis of macroheterocyclic peptidomimetic inhibitors of the aspartic protease β-site amyloid precursor protein cleaving enzyme (BACE)

Article abstract of DOI:10.1021/jm060154a

Based on the X-ray cocrystal structure of the Tang-Ghosh heptapeptide inhibitor 1 (OM00-3), a series of macroheterocyclic analogues were designed and synthesized. Analogues containing dithia, dioxa, oxathia, and carbathia macrocycles were synthesized by m

Full text of DOI:10.1021/jm060154a

4544
J. Med. Chem. 2006, 49, 4544-4567
Structure-Based Design and Synthesis of Macroheterocyclic Peptidomimetic Inhibitors of the
Aspartic Protease â-Site Amyloid Precursor Protein Cleaving Enzyme (BACE)
Stephen Hanessian,*,† Gaoqiang Yang,† Jean-Michel Rondeau,‡ Ulf Neumann,‡ Claudia Betschart,‡ and
Marina Tintelnot-Blomley‡
Department of Chemistry, UniVersite´ de Montre´al, C. P. 6128, Station Centre-Ville, Montre´al, Quebec H3C 3J7, Canada, and
NoVartis Institutes for BioMedical Research, NoVartis Pharma AG, Postfach, CH-4002 Basel, Switzerland
ReceiVed February 10, 2006
Based on the X-ray cocrystal structure of the Tang-Ghosh heptapeptide inhibitor 1 (OM00-3), a series of
macroheterocyclic analogues were designed and synthesized. Analogues containing dithia, dioxa, oxathia,
and carbathia macrocycles were synthesized by methods relying on ring-closing olefin metathesis for the
dioxa analogues and by alkylation of thiolates or bisthiolates for the others. Molecular modeling suggested
that the incorporation of piperidine units appended to the macrocycles improved interactions through additional
H-bonds and introduced further rigidity. These were synthesized in enantiomerically pure form using enzyme-
catalyzed desymmetrization and diastereomer separation. Inhibitory activity on â-site amyloid precursor
protein cleaving enzyme (BACE) was observed with several macroheterocyclic inhibitors and structure-
activity relationship (SAR) correlations were deduced. Cocrystal structures of two synthetic analogues revealed
interesting and unexpected binding interactions.
Introduction
between P2 and P3 are presented.6 In contrast to the first
examples with linkers between functional groups in the hydro-
philic S2 and S4 pockets, in this latter case, the linker consists
of a pure carbon chain located in the hydrophobic S1 and S3
environment. Again, compared with similar open-chain ana-
logues a slight improvement in activity was observed. In
addition, cellular activity was achieved with the compounds
linking the nitrogen of the amide bond between P2 and P3. This
is most likely due to better permeability gained by the
elimination of a H-bond donor.
There is substantial evidence that â-amyloid plays an
important role in the pathogenesis of Alzheimer’s Disease. The
generation of this short peptide is initiated by cleavage of a
larger precursor protein by the aspartic protease BACE (â-site
amyloid precursor protein cleaving enzyme, â-secretase). BACE
is therefore recognized as one of the most promising targets
for a disease-modifying treatment of Alzheimer’s Disease and
many research efforts are aiming at the identification of suitable
inhibitors as drug candidates.1
In this paper, we report on the design and synthesis of 15- to
17-membered macrocyclic hydroxyethylene inhibitors where P1
and P3 are connected through thioether or ether linkages, as
well as on novel bicyclic macrocycles encompassing a piperidine
ring. Statin-derived bis-thioether macrocycles have been studied
already as inhibitors of pepsin and penicillopepsin.7 Modeling
and overlays with the published X-ray structure of 1 (OM00-3)
suggested that this principle should also be applicable for
inhibitors of BACE (Figure 1). Furthermore, novel bicyclic
macrocycles containing a basic piperidine ring have been
designed to pick up additional interactions with the enzyme.
Although in drug discovery the ultimate goal usually is to
identify non-peptidic inhibitors, very often the first step in the
process toward such a compound is through substrate analogues.
It is well established that protease substrates have to adopt an
extended â-strand conformation to be recognized and cleaved
by the enzyme.2 Accordingly, such protease inhibitors are
designed to mimic essential features of peptides in â-strand
conformations. Macrocyclization is an established method to
pre-organize and stabilize this bioactive conformation.3 It has
been applied successfully for a number of proteases, in particular
aspartic proteases. In many cases, the activity, cell permeability,
oral availability, or proteolytic stability could be improved
considerably compared with the open chain analogues.4
Only a limited number of macrocyclic inhibitors of BACE
have been reported in the literature so far. A first paper reports
on cycloamide-urethane-derived compounds linking the P2 and
P4 moieties of a hydroxyethylene peptidomimetic inhibitor.5 The
compounds were synthesized by ring-closing olefin metathesis,
and in the best case, a gain in activity of approximately an order
of magnitude was achieved by going from the open precursor
to the ring-closed inhibitor. In addition, increased cellular
activity was observed when compared with similar open-chain
analogues. In a more recent publication, macrocyclic inhibitors
linking P1 with either P3 or the nitrogen of the amide bond
Results and Discussion
Chemistry. For the synthesis of the dioxa O/O macrocycles,
we relied on the now venerable Grubbs olefin metathesis
reaction8 of appropriately spaced bis-O-allyl intermediates as
shown in a disconnective analysis in Figure 2. We had also
hoped that the mixed oxathia macrocycles could be prepared
by such a carbocyclization. However, after initial exploratory
studies, it became evident that the synthesis of the dithia variants
would require a different methodology due to the incompatibility
of the Grubbs reagent with the presence of two thioether-type
groups. The bis-O-allyl and bis-O,S-allyl ether intermediates
would be generated from appropriate hydroxymethyl amino
acids such as serine or cysteine for the P2 site, and a new
δ-hydroxymethyl-δ-amino acid. The latter would originate from
the versatile Garner’s aldehyde.9
* Corresponding author. Tel (514) 343-6738. Fax (514) 343-5728.
E-mail: stephen.hanessian@umontreal.ca.
Addition of the organozinc acetylide, prepared from methyl
propiolate to 1 at -78 °C afforded the desired 2 (57%) and its
† Universite´ de Montre´al.
‡ Novartis Institutes for BioMedical Research.
10.1021/jm060154a CCC: $33.50 © 2006 American Chemical Society
Published on Web 06/24/2006

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4545
Scheme 1a
Figure 1. (A) Tang-Ghosh BACE inhibitors 1 (OM00-3) and (B)
proposed heteromacrocyclic pseudopeptidomimetic.
Figure 2. Disconnective analysis of the heteromacrocyclic pseudopep-
tides.
4-epimer 3 (5%) (Scheme 1). Although zinc acetylides have
been added to Garner’s aldehyde and the corresponding L-
cysteine variant, the analogous reaction with methyl propiolate
with a favorable stereochemical ratio is, to the best of our
knowledge, unprecedented. After a number of conditions
involving bases and additives were explored, the best ratio of
12:1 in favor of 2 was obtained with n-BuLi/ZnBr2 (or ZnCl2)
in ether. Catalytic reduction of 2 led to the saturated ester 4.
The minor isomer 3 could be oxidized to the acetylenic ketone,
the triple bond could be reduced to 5, and the resulting
compound could be subsequently treated with sodium borohy-
dride in methanol to give 4. Treatment of 4 with AcOH in
toluene at reflux temperature afforded the lactone 6, which was
alkylated via the lithium enolate to give 7 in 70% yield as a
single isomer. Cleavage of the acetal to 8 and O-allylation using
allyltrichloroacetimidate and triflic acid10,11 gave the lactone 9
in excellent overall yield. Treatment of 9 with butylamine
effected ring opening to give the butylamide 10.
a Reagents and conditions: (a) BuLi, methyl propiolate, Et2O, -78 °C,
then ZnBr2, Et2O, -78-0 °C, then Garner’s aldehyde, 62%; (b) Pd/C/
BaSO4, H2, AcOEt, 95%; (c) (i) Dess-Martin periodinane, 75%, (ii) Pd/C,
H2, 96%; (d) NaBH4, MeOH, 85%; (e) AcOH, toluene, 95%; (f) LiHMDS,
THF, then MeI, 70%, (g) TsOH, THF-H2O, 75%; (h) allyl trichloroace-
timidate, TfOH, CH2Cl2, 80%; (i) C4H9NH2, 40%; (j) (i) TFA, CH2Cl2, (ii)
N-Boc-Ala, PyBOP, DIEA, CH2Cl2, 85%; (k) (i) TFA, CH2Cl2, (ii) N-Boc-
O-allyl-SerOH, PyBOP, DIEA, CH2Cl2, 67% for 12; N-Boc-S-allyl-Cys,
PyBOP, DIEA, CH2Cl2, 75% for 13; N-Ac-S-allyl-Cys, HOBt, EDC, DCM-
H2O, 27% for 14; (l) Grubbs second generation catalyst 20-30 mol %,
CH2Cl2, 34% for 15, 25% for 17, 23% for 18; (m) Pd/C, H2, 91%.
desired product. However, using the second generation cata-
lyst13,14 (20 mol % in CH2Cl2) gave the dioxa-O/O macrocycle
15 as an inseparable mixture of cis and trans isomers in 34%
yield. Catalytic reduction led to the saturated macrocycle 16 in
91% yield.
The oxathia macrocycle was synthesized via the same
protocol (Scheme 1). Thus, coupling of the amine from 11 with
Boc-Cys(allyl)-OH proceeded smoothly to give the bis-O,S-allyl
dipeptide 13 in 75% yield. Carbocyclization via ring closure
Cleavage of the N-Boc group and coupling with Boc-Ala-
OH in the presence of PyBOP gave the dipeptide 11 in 85%
yield. Further extension with Boc-Ser(allyl)-OH led to the bis-
O-allyl precursor 12 in 67% yield. Attempted carbocyclization
with the Grubbs first generation catalyst12 did not lead to any

4546 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
Scheme 2a
Scheme 3a
a Reagents and conditions: (a) (i) TFA, CH2Cl2, (ii) 3-benzylsulfanyl
propionic acid, PyBOP, DIEA, CH2Cl2, 70%; (b) Na-NH3 (liq), cis-1,4-
dibromobutene, 51%; (c) Na-NH3 (liq), trans-1,4-dibromobutene, 45%.
the resulting bis-thiolate with a variety of dibromides gave the
corresponding dithia macrocycles 23-28 in modest to good
yields depending on the nature of the products. Four analogues
were also deprotected to the amines, which were converted to
the corresponding N-acetyl variants 29-32 by acetylation with
acetic anhydride.
To probe the interactions of the P3-P4 amide, we deemed it
necessary to synthesize dithia macrocycles with cis- and trans-
alkene bridges but lacking the terminal N-Boc or N-Ac group
(Scheme 3). The common intermediate 19 was cleaved to the
amine then coupled with Boc-Ala-OH as usual. Further exten-
sion with 3-S-benzylpropionic acid gave the bis-S-benzyl
dipeptide 33. Reductive cleavage of the benzyl groups and bis-
alkylation with cis-1,4-dibromobutene and trans-1,4-dibro-
mobutene gave the corresponding dithia macrocycles 34 and
35 in 51% and 45% yields, respectively.
a Reagents and conditions: (a) BnSH, PMe3, ADDP, CH2Cl2, 66%; (b)
C4H9NH2, AlMe3, CH2Cl2, 88%; (c) (i) TFA, CH2Cl2, (ii) N-Boc-Ala,
PyBOP, DIEA, CH2Cl2, 90%; (d) (i) TFA, CH2Cl2, (ii) N-Boc-S-Bn-Cys,
PyBOP, DIEA, CH2Cl2, 57%; (e) Na-NH3 (liq), then BrCH2-R-CH2Br;
(f) (i) TFA, CH2Cl2, (ii) Ac2O, DMF, NaHCO3.
Previous SAR data5,22-26 and preliminary results from our
laboratory27-29 had shown a beneficial effect of a valine residue
at P2′ in inhibition experiments on BACE. We decided to
synthesize an extended variant of 27 and 28, incorporating a
valine residue and capping with a butylamide (Scheme 4). Thus,
19 was treated with aq LiOH, and the resulting Li+ carboxylate
was carefully acidified to give the free carboxylic acid 36 in
91% overall yield. Coupling with H-Val-n-butyl in the presence
of PyBOP gave the peptide 37 in 86% yield. Cleavage of the
t-butyldimethylsilyl (TBS) group afforded the corresponding
hydroxyl compound 38. A more expedient route was to treat
the lactone 19 directly with H-Val-n-butyl in the presence of
2-hydroxypyridine and refluxing toluene30,31 to afford 38 in 66%
yield. Extension to 39 and coupling with Boc-Cys(Bn)-OH gave
40 in excellent overall yield. Reductive cleavage and bis-
alkylation as described above gave the cis- and trans-dithia
macrocycles 41 and 42 in 24% and 22% yields, respectively.
Various attempts to increase the yields of bis-alkylations in this
and related cases were unsuccessful.
The series of oxathia macrocycles and dithia macrocycles
described above was tested for inhibition of BACE under
standard conditions.32 Although little or only marginal inhibition
was observed for the majority of the analogues, we found that
the trans-dithia macrocycle 42 exhibited an IC50 of 156 nM
against BACE. However, the isomeric cis macrocycle 41 showed
10-fold weaker activity. The X-ray structure of 42 in a complex
with human BACE was solved at a resolution of 2.10 Å (see
Discussion).
metathesis of 13 using the second generation Grubbs catalyst
(30 mol % in CH2Cl2)13,14 afforded the desired oxathia macro-
cycle 17 as a mixture of cis and trans isomers in 25% yield. To
explore the influence of the N-terminal group, we also prepared
the N-acetyl macrocycle 18 from acyclic precursor 14. Attempts
to improve the yields of these carbocyclizations by variation of
catalyst load or concentration were not successful.
We next turned our attention to the dithia macrocycles. Since
the Grubbs macrocylization of bis-S-allyl precursors corre-
sponding to 13 was not possible, presumably due to the strong
coordination with the catalyst, we adopted a macrocyclization
protocol based on an intramolecular bis-thioetherification with
appropriate dibromides and a bis-thiolate.7,15-17 By varying the
length of the dibromoalkenes and alkanes, we envisaged the
preparation of dithia macrocycles having 15-17-membered
pseudopeptide rings. Rather than utilize the L-cysteine equivalent
of the Garner aldehyde18 and to reinvestigate stereocontrolled
routes to the corresponding acetylenic ester similar to 2, we
chose to use the advanced intermediate from the previous route
(Scheme 1) and to introduce a benzylthio group via a Mitsunobu
reaction (Scheme 2).19 Thus, treatment of 8 with benzyl
mercaptan, in the presence of trimethylphosphine and ADDP
(azodicarbonyldipiperidine),20 led to the corresponding ben-
zylthio analogue 19 in 66% yield. Ring opening to the acyclic
butylamide 20, followed by peptide coupling with Boc-Cys-
(Bn)-OH gave the bis-benzylthio dipeptide 22 in 57% yield.
Reductive cleavage with Na/NH3 (liquid),21 and treatment of

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4547
Scheme 5a
Scheme 4a
a Reagents and conditions: (a) (i) LiOH, DME-H2O, (ii) TBSCl,
imidazole, THF, 91% for two steps; (b) Val-N-nBu, PyBOP, DIEA, CH2Cl2,
86%; (c) TsOH, MeOH, 50%; (d) Val-N-nBu, 2-hydroxypyridine, toluene,
66%; (e) (i) TFA, CH2Cl2, (ii) N-Boc-Ala, PyBOP, DIEA, CH2Cl2, 82%;
(f) (i) TFA, CH2Cl2, (ii) N-Boc-S-Bn-Cys, PyBOP, DIEA, CH2Cl2, 61%;
(g) Na-NH3 (liq), cis-1,4-dibromobutene, 24%; (h) Na-NH3 (liq), trans-
1,4-dibromobutene, 22%.
a Reagents and conditions: (a) (i) TMEDA, sec-BuLi, THF, (ii) CO2,
HCl, 80%; (b) TMSEOH, DEAD, Ph3P, THF, 72%; (c) BnSH, NaOMe,
MeOH, 78%; (d) TFA, DCM, 75%; (e) (Boc)2O, NaHCO3, MeOH, 90%;
(f) TBAF, THF, quant; (g) 21, PyBOP, DIEA, CH2Cl2, 62%; (h) (i) Na-
NH3 (liq), (ii) trans-dibromobutene, 54%; (i) TFA/DCM, quant.
NH3(liquid) generated the corresponding sodium thiolates, which
upon alkylation with trans-1,4-dibromobutene gave the desired
bicyclic dithia macrocycles 51 and 53 in 54% yield after
separation by column chromatography. Cleavage of the N-Boc
group gave the corresponding piperidine dithia macrocycles 52
and 54, respectively. The stereochemical identity of 52 was
deduced from the X-ray structure of a cocrystal complex with
BACE (see below). While the (2R,3R)-isomer 54 showed only
weak inhibitory activity against BACE (45% inhibition at 10
µM), the (2S,3S)-isomer 52 showed an IC50 of 190 nM, which
was in contradiction to the modeling study (see Discussion).
The isomeric (3R,4S)-bicyclic piperidine dithia macrocycle
corresponding to 63 (and its 3S,4R-diastereomer 69) were
synthesized starting with N-Boc-4-ketopiperidine 55 (Scheme
6). Treatment with lithium diisopropylamide (LDA) and trapping
the enolate with Comins’s reagent36,37 gave the enol triflate 56,
which was transformed to the corresponding methyl ester 57
using a Pd-catalyzed carbonylation reaction.38 Conjugate addi-
tion of benzyl mercaptan in methanolic sodium methoxide gave
a racemic mixture of cis-3-benzylthioethers 58. Treatment of
the mixture with pig liver esterase in phosphate buffer (pH 7.2)
afforded the ester 59 and acid 60 in quantitative yield. The
identity of the ester 59 was ascertained from a single-crystal
X-ray structure.32 Coupling of the amine derived from 21 with
60 afforded the (3R,4S)-piperidine linear peptide 61 in 68%
yield. Reductive cleavage of the benzyl groups and bis-alkylation
with trans-1,4-dibromobutene gave the intended macrocycle 62
in 39% isolated yield. Cleavage of the N-Boc group gave the
corresponding piperidine dithia macrocycle 63 in quantitative
yield. A similar protocol was followed for the synthesis of the
diastereoisomeric (3S,4R)-piperidine dithia macrocycles 68 and
In addition to the above-described inhibitors, modeling studies
also suggested bicyclic piperidine macrocycles as potential
inhibitors so as to benefit from specific interactions with
individual amino acid residues in the P3 pocket, such as Gly11
and Thr232 (see Discussion). We synthesized 2,3-disubstituted
and 3,4-disubstituted piperidine dithia macrocycles 52, 54, 63,
and 69 ,respectively, in diastereomerically pure form (Schemes
5 and 6).
The synthesis of these bicyclic macrocycles presented sig-
nificant challenges. Modeling studies suggested the need for a
(2R,3R) absolute configuration for the piperidine moiety as in
54. Our synthetic route allowed us to prepare both diastereo-
meric final products with either (2S,3S) or (2R,3R) configuration
as in 52 and 54, respectively. Results later showed that
unexpectedly the (2S,3S)-diastereomer 52 had higher activity
compared with 54 (see Discussion).
Racemic N-Boc-3-methoxy piperidine 43 was treated with
sec-BuLi in the presence of tetramethylethylenediamine (TME-
DA) to generate the corresponding R-lithiated heterocycle33
(Scheme 5). Quenching with CO2 and workup led to the R,â-
unsaturated acid 44 in excellent yield. Esterification to the
trimethylsilylethyl ester 45 and treatment with benzyl mercaptan
in methanolic sodium methoxide34,35 gave a 78% yield of a 1:1
mixture of diastereomeric N-Boc-3-S-benzyl pipecolic acid esters
46. Cleavage of the Boc group allowed the separation of the
racemic cis and trans isomers. The cis isomer of 47 was
transformed again to the N-Boc ester 48, and the (trimethylsilyl)-
ethyl (TMSE) ester was cleaved leading to free acid 49. Peptide
coupling with the amine derived from 21 gave amides 50 as a
1:1 inseparable mixture of diastereomers. Treatment with Na/

4548 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
Scheme 6a
Scheme 7a
a Reagents and conditions: (a) (i) LDA, THF, (ii) Comins’s reagent,
THF, 81%; (b) Pd(OAc)2, Ph3P, CO, DMF, MeOH, 77%; (c) BnSH,
NaOMe, MeOH, 89%; (d) PLE, buffer, pH 7.2, 49%; (e) 21, PyBOP, DIEA,
CH2Cl2, 68%; (f) (i) Na-NH3 (liq), (ii) trans-dibromobutene, 39%; (g) TFA,
CH2Cl2, quant; (h) (i) LiOH, THF, H2O, (ii) TMSEOH, EDCI, DMAP,
74% for two steps; (i) BnSH, NaOMe, MeOH, 82%; (j) (i) TBAF, (ii) 21,
PyBOP, DIEA, CH2Cl2, 68%; (k) Na-NH3 (liq), then trans-1,4-dibro-
mobutene, 48%.
a Reagents and conditions: (a) MeOH, reflux, 50%; (b) (i) Pd/C, H2,
HOAc, (ii) (Boc)2O, MeOH, NaHCO3 76%; (c) (i) (COCl)2, toluene, (ii)
NaBH4, THF, 78%; (d) Dess-Martin periodinane, 90%; (e) Ph3PdCHCO2-
TMSE, CH2Cl2, 93%; (f) Pd/C, H2, AcOEt, 98%; (g) TBAF, THF, 93%;
(h) LiOH, THF-H2O, quant; (i) 21, PyBOP, DIEA, CH2Cl2, 64%; (j) (i)
Na-NH3 (liq), (ii) ADDP, PMe3, CH2Cl2, 42% for two steps; (k) TFA,
CH2Cl2, quant.
69 starting from 64, which was prepared from 3-keto-4-
carbomethoxy N-benzylpiperidine.39,40 In this case, it was more
practical to separate the diastereomeric macrocycles 61 and 67,
rather than to use enantiopure 59.
Our modeling studies also suggested that the carba/thia
analogues 82 and 84 of the two 2,3-disubstituted piperidine
bicyclic macrocycles would be potential inhibitors of the enzyme
(Scheme 7). We therefore in parallel also developed methods
for the stereocontrolled synthesis of macrocycles in this new
series. For practical reasons, we utilized sequences that would
give both diastereomers to maximize information with regard
to stereochemical differences.
The commercially available 2,3-pyridinedicarboxylic anhy-
dride was subjected to methanolysis, and the resulting acid 70
was converted through well-precedented steps to the extended
R,â-unsaturated ester 72, then aldehyde 74, which was extended
to the allylic alcohol 77 (Scheme 7). Coupling of the corre-
sponding carboxylic acid 78 with the amine derived from 21
afforded a separable mixture of dipeptides 79 and 80. Cleavage
of the S-benzyl group, followed by intramolecular Mitsunobu
thioetherification, gave the bicyclic piperidine carba/thia mac-
rocycles 81 and 83, respectively. Cleavage of the N-Boc group
by acidic treatment gave the free piperidine bicyclic macrocycles
82 and 84, respectively.
An enantio-enriched version was also achieved to assign
absolute stereochemistry to the separated diastereomers 82 and
84 and to eventually secure their synthesis as pure diastereomers.
Thus, S-1-phenylethylamine was transformed to the bis-alkylated
enantiopure glycine ester 85 following Normant’s procedure41,42
(Scheme 8). Base-catalyzed cyclization in the presence of CuCN
and allyl bromide gave the chain-extended piperidine 86 in 65%
yield. Oxidative cleavage of the terminal olefin with OsO4 in
the presence of NaIO4 afforded the aldehyde 87. Reductive
cleavage of the R-methylbenzyl group and further protection
as N-Boc derivative afforded 88, which corresponds to the
enantiopure form of 74. Thus, access to enantiopure 82 could
be achieved via an asymmetric synthesis.
Finally, the diastereomeric 3,4-disubstituted piperidine carba/
thia variants 99 and 101 were synthesized from the previously

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4549
Scheme 8a
corresponding allylic alcohol 94. Hydrolysis of the ethyl ester
and coupling of the resulting acid 95 with the amine derived
from 21 gave a 1:1 mixture of the dipeptides 96 and 97, which
were easily separated by flash column chromatography. Cleav-
age of the benzylthioether and intramolecular Mitsunobu
thioetherification, as previously described in Scheme 6, gave
the isomeric macrocycles 98 and 100, which were individually
converted to the bicyclic piperidine carbathio macrocycles 99
and 101, respectively (relative cis stereochemistry).
Biological Data and Structure-Activity Relationships.
SAR of Dithia Macrocycles. Statin-derived bis-thioether mac-
rocycles have been shown to have similar activity on pepsin
compared with their open chain analogues.7 Hydroxyethylene-
type open-chain inhibitors 103 and 104, spanning P3 to P2′, were
available from previous unpublished studies in our laboratory.
These showed submicromolar activity on BACE and nanomolar
activity on pepsin (Table 1). We prepared a number of closely
related N-Ac dithia macrocycles linking P1 and P3 side chains
(Table 1, 29-31). A dramatic loss of activity was found (IC50
> 10 µM) against BACE, while a less pronounced loss in
activity was observed for pepsin and cathepsin D (Table 1).
These two enzymes were chosen for comparison because they
are the most similar structurally known aspartic proteases (except
for the almost identical BACE2).
a Reagents and conditions: (a) (i) DCM, 4 Å MS, rt, (ii) NaBH4, MeOH,
(iii) BrCH2CO2Me, Et3N, DMSO, 80% for three steps; (b) (i) LDA, ZnBr2,
Et2O, (ii) CuCN, AllylBr, THF, 65%; (c) OsO4, dioxane-H2O, NaIO4, 61%;
(d) Pd/C, H2, (Boc)2O, MeOH, 54%.
Scheme 9a
The 15- and 16-membered N-Boc saturated macrocycles were
found to have about equal potency for BACE, while the 17-
membered ring had clearly lower activity (Table 1, 23 and 24
compared with 25). For pepsin, the ring size does not seem to
affect the activity, while for cathepsin D, the larger rings are
preferred over the smaller 15-membered ring.
Compared with the saturated inhibitor 23, the conformation-
ally restricted trans-olefin 28 in the 15-membered series showed
increased activity on BACE, while the corresponding cis-olefin
27 was only slightly weaker. Molecular modeling could not
reveal any clear differences between the saturated linker and
the two olefinic counterparts. The data suggests that in the trans-
olefin, the flexibility of the chain is restricted in a favorable
conformation, leading to better binding and increased activity
compared with the saturated analogue. As predicted in the
model, the aromatic linker in compounds 26 and 32 is too bulky
to fit in the pocket, and the activity is therefore lost.
The replacement of the Boc group by an acetyl consistently
results in lower activity against BACE, as well as cathepsin D
and pepsin (Table 1, 23-26 compared with 29-32) as reported
by other groups.46 The S4 pocket is substantially more hydro-
phobic in cathepsin D (e.g., Leu236, Leu 292, Leu303, and
Met307 in cathepsin D correspond to Asn233, Arg307, Lys321,
and Ser325 in BACE, respectively), which may explain the
larger contribution of the Boc group to binding potency. The
small beneficial effect observed with BACE compared with
cathepsin D suggests that in this case, the tert-butyl moiety of
the Boc group cannot make good hydrophobic contacts due to
the more hydrophilic nature of the S4 pocket. This inference is
supported by the X-ray analysis of the BACE complex with 42
(see below).
a Reagents and conditions: (a) (i) Mg, BrCH2CH2CH2OTBS, THF, then
CuI, (ii) 64, TMSCl, HMPA, 68%; (b) TBAF, THF, 90%; (c) Dess-Martin
periodinane, 80%; (d) Ph3PdCHCO2TMSE, CH2Cl2, 75%; (e) TBAF, THF,
63%; (f) (i) ClCO2Et, Et3N, THF, (ii) NaBH4, MeOH, 60%; (g) LiOH,
THF-H2O, 96%; (h) 21, PyBOP, DIEA, CH2Cl2, 70%; (i) (i) Na-NH3
(liq), (ii) ADDP, PMe3, imidazole, CH2Cl2, 30%; (j) TFA, DCM, quant.
While both N-Boc and N-acetyl groups allow for the positive
interaction of the NH with Thr232, the loss of this interaction
results in considerably lower activity as seen in the correspond-
ing amino analogues compounds 34 and 35 (compared with 27
and 28).
SAR of Oxygen-Linked Macrocycles. In a limited program,
we also explored the dioxa and mixed oxa/thia analogues of
the dithia macrocycles (Table 2). For the interpretation of the
results, it has to be considered that these compounds were
described ester 64 (Scheme 9). A mixed cuprate reagent prepared
from 3-tert-butyldimethylsilyloxy propyl bromide43 was added
to 64 to give an 8:1 cis/trans mixture of adducts 89. Cleavage
of the TBS group led to the corresponding alcohols, which were
separable by flash column chromatography. Oxidation of the
racemic cis isomer 90 with the Dess-Martin periodinane
reagent,44,45 followed by Wittig homologation, gave R,â-
unsaturated ester 92, which was selectively transformed to the

4550 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Table 1. SAR of Dithia Macrocycles and Open-Chain References
Hanessian et al.
Table 2. SAR of Oxygen-Linked Macrocycles
IC50
IC50
IC50
compd
BACE CathD pepsin
no.
R, X, Y
linker
(µM)
>10
20.3
(µM)
(µM)
16
15
17
18
Boc, O, O (CH2)4
Boc, O, O CH2sCHdCHsCH2
Boc, S, O CH2sCHdCHsCH2
1.11
0.91
0.325
0.060
a
a
a
0.51 0.11 <0.01
1.12 6.0
Ac, S, O
CH2sCHdCHsCH2
0.17
a Olefins were mixtures of cis and trans isomers.
Table 3. Elongation in P′
IC50
BACE
(µM)
IC50
CathD
(µM)
IC50
pepsin
(µM)
compd
no.
linker
41
42
cis-CH2sCHdCHsCH2
trans-CH2sCHdCHsCH2
1.97
0.156
0.050
0.011
<0.01
<0.01
on inhibition of cathepsin D and pepsin was marginal. The
replacement of the N-Boc group by N-acetyl resulted in the same
small effect as seen before (Table 2, 17 compared with 18).
Due to the difficulty to control the geometry of the olefins,
further studies were continued only in the dithia series (despite
the tendency for higher potency of the mixed analogues).
Effect of Elongation in P′. The compounds described so far
do not contain an amino acid residue in P2′ but rather a
butylamide capping group filling the respective pocket. As
already demonstrated in other series,27 the elongation of the P′
side by a capped P2′ amino acid increases the activity. In the
present case, the introduction of an additional valine in P2′
resulted in an increase of activity by about one order of
magnitude (Table 3). This is true for BACE as well as cathepsin
D and comparable to the effect found in previous series.27 The
effect on pepsin could not be quantified by our assay system,
but the high activity (<10 nM) is well in line with the activity
reported by Szewczuk et al.7 for an analogous statin-derived
trans-butene-linked 15-membered dithia macrocycle (<1 nM).
Against BACE, the trans-dithia macrocycle 42 exhibited an IC50
of 156 nM and was submitted for cocrystallization. The structure
of the complex was solved to a resolution of 2.10 Å (Figure 3)
and supported our original hypothesis, showing a very good
match of the experimental structure to the one predicted by the
model.
In particular, a structural overlay of the 1 (OM00-3) complex
(Figure 3) with the macrocyclic compound 42 demonstrated that
the peptide backbones of both compounds superimpose remark-
ably well. All important binding interactions originally observed
in the complex with the linear peptidomimetic inhibitor were
in fact nicely mimicked by the macrocyclic inhibitor. Critical
hydrogen-bonded interactions to the BACE active site, including
those to Gly34, Pro70, Thr72, Gln73, Gly230, and Thr232, are
also observed with 42, further confirming that the binding of
the hydroxyethylene transition state isostere is not altered as a
consequence of the incorporation of the macrocyclic motif 42.
Furthermore, and in comparison to the 1 complex, only a few
structural changes affecting the enzyme active site are observed,
a IC50 not determined.
obtained as undefined mixtures of cis- and trans-olefins.
Nevertheless, we can conclude that the dioxa analogues are
weaker on all three enzymes compared with the dithia macro-
cycle (Table 2, 15 and 16 compared with 23, 27, and 28). In
the case of BACE, this seems to be due to unfavorable
interactions of the oxygen in this specific position in P3. The
properties of this position are determined by the closely located
lipophilic Ile110 and the proximity of the carbonyl oxygen of
Gly11. The detrimental effect of an oxygen atom at this
particular position was also observed in other peptidomimetic
macrocyclic series (unpublished results). The mixed analogue
17 showed improved activity on BACE compared with the dithia
analogues 27 and 28, indicating a slightly positive effect of the
replacement of sulfur by an oxygen in the P1 linker. The effect

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4551
Figure 4. Overlay of OM00-3 (orange) with models of bicyclic
inhibitors (54, top, and 69, bottom) showing the intended interactions
and expected conformation.
Figure 3. X-ray structure of 42 (dark green)-BACE complex (top)
and overlay of the X-ray structures of BACE complexes with 42 (this
work, dark green) and 1 (PDB 1M4H, orange) (bottom).
Table 4. SAR of Bicyclic Macrocycles
the main difference between the two complexes being a small
induced fit of the enzyme flap, which can be rationalized by
the presence of smaller substituents at P2 and the leaner
substituent at P1 in 42. The butylamide cap binds to the S3′
subsite and appears to be a good replacement for the P3′ glutamic
acid of 1, contributing similar hydrophobic contacts to the
enzyme flap as well as to the H-bonded interaction to the Pro70
oxygen. Surprisingly, the N-terminal Boc protecting group was
not visible in the electron density maps, suggesting that this
part of the molecule remains mobile in the complex or adopts
several binding modes. This observation is consistent with the
fact that the S4 pocket of BACE is large, very hydrophilic, and
highly exposed to solvent. Also, our in vitro inhibition data show
that an N-terminal Boc group is only marginally better than
the corresponding N-acetyl derivative against BACE but clearly
more active than the free amine 102 as reported for other cases.6
The electron density for the trans-butene linker in the macro-
cycle was weak, leaving the position of the double bond
undefined, indicating that conformational disorder is also
affecting this region of the molecule, although to a lesser extent.
This observation suggests that the trans-dithia bridge could be
present in more than one tight fitting conformation in the S1
and S3 subpockets, which are both large enough to accommodate
a branched alkyl side chain such as leucine, as in OM00-3 for
instance. Indeed, flexible docking calculations indicate that
several conformations in the area of the double bond are possible
without affecting the overall position of the ligand.
Bicyclic Scaffolds. In addition to the above-described mac-
rocycles, we also explored two bicyclic piperidine scaffolds with
a positively charged nitrogen represented by 2,3- and 3,4-
disubstituted 54 and 69, respectively. They were designed in
the model to each pick up one of two possible interactions, either
with the Thr232 OH (as in 1 and other peptidomimetic
inhibitors) or with the Gly11 CO (Figure 4). These interactions
were intended to replace and compensate for the interactions
of the P3-P4 amide or carbamate group in the former structures.
To our disappointment, the designed compound 69 was found
to be inactive against BACE, while compound 54 showed weak
activity (Table 4). In comparison with compound 35 (lacking
the piperidine ring), there was no gain in activity for 69 but a
IC50
BACE CathD
(µM) (µM)
IC50
IC50
pepsin
(µM)
compd
no.
stereoisomer
X
V
W
69
63
54
52
99
101
82
84
A
B
A
B
A
B
A
B
S
NH CH2 >10
NH CH2 >10
CH2 NH ∼12
>10
∼2
S
S
S
∼9
∼10
∼0.2
∼0.01
CH2 NH
0.19
0.01
<0.01
CH2 NH CH2 >10
CH2 NH CH2 >10
CH2 CH2 NH >10
CH2 CH2 NH >10
>10
>10
>10
0.092
0.51
>10
>10
6.9
slight gain for 54, indicating that the interaction with Thr232 is
more feasible than the interaction with Gly11. The observed
parallel gain in activity for 54 compared with 35 in cathepsin
D and pepsin can be attributed to a similar positive interaction
of the piperidine nitrogen with the Ser235 residue in the position
corresponding to Thr232 in BACE. Since the syntheses for both
bicyclic scaffolds started from racemic materials and involved
a separation of isomers in a later step, we also had access to
diastereomers 52 and 63. As for 69, the diastereomeric
compound 63 was inactive against BACE and compared with
35, which does not have a piperidine ring, did not show
improvement for cathepsin D and pepsin either. However,
compound 52 (the diastereomer of the weak inhibitor 54)
showed surprisingly good activity (Table 4). Compared with
the elongated macrocycle 42, 52 lacks the P4 and P3′ moieties.
Nevertheless, the two compounds are equipotent against all
enzymes. This was difficult to understand on the basis of the
model, and the compound was therefore submitted for cocrys-

4552 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
defined for most inhibitor atoms, it was again weaker for the
trans-butene linker, with an undefined position of the double
bond. This observation suggests that the conformational flex-
ibility already observed for the trans-dithia linker of compound
42 is also exhibited by the bicyclic piperidine macrocyclic
compound 52.
In an attempt to better understand the discrepancy between
the model and the results for the bicyclic compounds we tried
a functional modification in the macrocycle by replacing one
sulfur atom by carbon. Unexpectedly, all the diastereomeric
carbathia bicyclic macrocycles (82, 84, 99, and 101), were
inactive against BACE, including the carbon analogue 84 of
the active inhibitor 52. The activities were found to be lower
than the respective dithia analogues for cathepsin D (Table 4).
Curiously, only the two carbathia analogues 82 and 84 showed
inhibition against pepsin (Table 4).
Figure 5. Overlay of the X-ray conformations of the BACE complexes
with 42 (dark green) and 52 (cyan).
Conclusion
The primary objective of this study was to demonstrate the
feasibility of linking P1 and P3 residues in acyclic BACE
inhibitors, which would result in macrocyclic structures. Beside
other advantages, these compounds were expected to show
improved activity through pre-organization of the bioactive
conformation. However, our expectations for activity on BACE
were not fulfilled, especially in comparison with the high activity
on pepsin. A cocrystal structure of one of the inhibitors in BACE
showed that despite the macrocyclization, the molecule still
seems to be relatively flexible, as could be concluded, for
example, from the weak electron density for the chain positioned
in the S1-S3 pockets. To improve interactions through additional
hydrogen bonds and to introduce further rigidity, novel bicyclic
macrocycles incorporating a piperidine moiety were designed.
Synthetic approaches for all possible diastereoisomers of the
piperidine moiety were developed. Surprisingly, the biological
results did not match the predictions from the model with respect
to the preferred stereochemistry. A cocrystal structure of the
most active inhibitor revealed a shift of the molecule that
unexpectedly placed the piperidine ring in the S3 pocket, while
forcing the P1-P3 chain into an unusual conformation and
orientation.
Figure 6. X-ray crystal structure of 52 (cyan)-BACE complex (top)
and overlay of crystal structures of 52 (cyan) and 1 (orange) (partial
surface to show S3 pocket) (bottom).
tallization. The structure could be solved to a resolution of 2.3
Å, and in contrast to the crystal structure of 42 with the enzyme,
it revealed some unexpected surprises.
Experimental Section
A comparison of the BACE complexes with 42 and 52 is
presented in Figure 5. The structure of the active site and the
conformation of the enzyme flap are similar in the two
complexes. However, the binding modes of these two trans-
dithia macrocyclic compounds differ substantially in several
respects. As expected, the butylamine group of 52 binds in S2′
and acts as a replacement of the valine side chain of 42, while
maintaining the key H-bonded interaction to Gly34. Modeling
of the originally suggested (2R,3R) isomer 54 predicted an
interaction of the piperidine nitrogen with Thr232. The active
diastereomer 52 indeed forms such a hydrogen bond of 2.9 Å
length. However, the position of the nitrogen is not as seen in
most cocrystal structures (e.g., 1) but instead is shifted by 1.5-2
Å toward the S3 pocket (Figure 6). Because of this shift, the
piperidine carbon chain fills nicely the hydrophobic S3 pocket.
As an additional striking difference, the trans-dithia bridge of
52 follows a completely different path in comparison to that
observed in the complex with 42. It seems surprising that such
good activity is exhibited by a compound with such an unusual
conformation of the macrocyclic chain, in particular because
the space usually occupied by P1 and P3, as seen in 1, is not
filled (see Figure 6). We speculate that this is due to the positive
interaction of the piperidine moiety in the S3 pocket as described
above. Interestingly, although the electron density was well
Solvents were distilled under positive pressure of dry argon
before use and dried by standard methods: THF and ether from
Na/benzophenone; CH2Cl2 and toluene from CaH2. All com-
mercially available reagents were used without further purification.
All reactions were performed under argon atmosphere. NMR (1H,
13C) spectra were recorded on Bruker AMX-300 and ARX-400
spectrometers in CDCl3, CD3OD, or D2O with solvent resonance
as the internal standard. Low- and high-resolution mass spectra were
recorded on VG Micromass, AEIMS 902, or Kratos MS-50
spectrometers using fast atom bombardment (FAB). The purity of
the macrocyclic target compounds was determined to be >95% by
LC/MS obtained on a Finnigan Surveyor MSQ spectrometer. Purity
of the compounds was determined by method A, Alltech Prevail
C18 column (250 mm × 4.6 mm) at 0.5 mL/min flow rate using a
gradient of 20-90% acetonitrile-water (0.1% trifluoroacetic acid),
and method B, Alltech Prevail C18 column (250 mm × 4.6 mm)
at 0.5 mL/min flow rate using 65% methanol-water (0.1%
trifluoroacetic acid). Optical rotations were recorded on a Perkin-
Elmer 241 polarimeter in a 1 dm cell at ambient temperature.
Analytical thin-layer chromatography was performed on Merck 60F
254 precoated silica gel plates. Flash column chromatography was
performed using 40-60 micron silica gel at increased pressure.
All melting points are uncorrected.
(4S,1′S)-4-(1-Hydroxy-3-methoxycarbonyl-prop-2-ynyl)-2,2-
dimethyl-oxazolidine-3-carboxylic Acid tert-Butyl Ester (2) and

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4553
(4S,1′R)-4-(1-Hydroxy-3-methoxycarbonyl-prop-2-ynyl)-2,2-di-
methyl-oxazolidine-3-carboxylic Acid tert-Butyl Ester (3). Butyl
lithium (1.6 M in hexane, 28 mL, 44.8 mmol) was added dropwise
into a solution of methyl propiolate (4.1 mL, 49.1 mmol) in Et2O
(200 mL) at -78 °C, the solution was stirred at the same
temperature for 1 h, and then a pre-prepared and pre-cooled solution
of zinc bromide (12.4 g, 55 mmol) in diethyl ether (100 mL) was
added through a cannula. The mixture was stirred at -78 °C to
room temperature for 2 h, then cooled to -20 °C, and a pre-cooled
solution of Garner’s aldehyde9 (4.1 g, 17.9 mmol) in Et2O (40 mL)
was added by a cannula. The mixture was stirred at -20 °C to
room temperature for 6 h, then cooled to -20 °C, and saturated
NH4Cl (50 mL) was added to quench the reaction. The mixture
was extracted with Et2O (3 × 100 mL), and the combined organic
layers were washed with brine, dried over MgSO4, and concentrated
under reduced pressure. Flash chromatography (hexane/AcOEt 3/1)
of the residue gave 2 (3.2 g, 57%) and 3 (0.27 g, 5%). For 2: [R]D
-79.3 (c 0.85, CHCl3), 1H NMR (CDCl3, 400 MHz, 50 °C) δ 4.69
(dd, 1H, J ) 8.4, 6.0 Hz), 4.32 (b, 1H), 4.15 (b, 1H), 4.05 (m,
2H), 3.74 (s, 3H), 1.64 (s, 3H), 1.49 (s, 12H); 13C NMR (CDCl3,
100 MHz) δ 155.3, 154.0, 95.2, 86.4, 82.4, 77.2, 71.4, 65.6, 61.9,
53.2, 28.7, 26.7, 24.5; MS (FAB) m/z 314 (M + H+), 258, 240,
214, 200; HRMS calcd for C15H23NO6 (M + H+) 314.1617, found
was added, the mixture was heated to reflux for 5 h and then cooled
to room temperature, and the solvent was removed under reduced
pressure. Flash chromatography of the residue gave the product 6
(0.27 g, 95%): [R]D -21.7 (c 0.4, CHCl3); 1H NMR (CDCl3, 400
MHz, 50 °C) δ 4.82 (b, 1H), 4.25 (b, 1H), 4.0 (dd, 1H, J ) 10.0,
6.3 Hz), 3.87 (d, 1H, J ) 10.0 Hz), 2.54 (m, 2H), 2.18 (m, 2H),
1.60 (s, 3H), 1.51 (s, 3H), 1.48 (s, 9H); 13C NMR (CDCl3, 100
MHz) δ 177.1, 153.6, 95.1, 81.2, 80.3, 79.2, 65.2, 59.5, 28.7, 26.8,
25.5, 23.6; MS (FAB) m/z 286 (M + H+), 230, 186, 172, 154;
HRMS calcd for C14H23NO5 (M + H+) 286.1654, found 286.1649.
(4S,2′S,4′R)-2,2-Dimethyl-4-(4-methyl-5-oxo-tetrahydro-furan-
2-yl)-oxazolidine-3-carboxylic Acid tert-Butyl Ester (7). To a
stirred solution of 6 (0.8 g, 3.16 mmol) in THF (30 mL) at -78 °C
under argon was added LiHMDS (1 M in THF, 4.7 mL) dropwise.
The mixture was stirred at -78 °C for 30 min, then methyl iodide
(0.39 mL, 6.4 mmol) was added dropwise, and the mixture was
stirred at -78 °C for 40 min. The reaction mixture was quenched
with saturated NH4Cl and extracted with AcOEt (3 × 100 mL),
and the combined organic layers were washed with brine, dried
over Na2SO4, and concentrated. The residue was purified by flash
chromatography to give 7 as an amorphous solid (0.5 g, 70%): [R]D
-1.6 (c 0.73, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 4.75 (b, 1H),
4.21 (b, 1H), 3.94 (dd, 1H, J ) 9.6, 6.2 Hz), 3.82 (m, 1H), 2.72 (b,
1H), 2.45(b, 1H), 2.33 (b, 1H), 1.93 (b, 1H), 1.63 (s, 3H), 1.57 (s,
3H), 1.49(s, 9H), 1.30 (d, 3H, J ) 6.8 Hz); 13C NMR (CDCl3, 100
MHz) δ 180.2, 179.8, 153.5, 152.3, 95.2, 94.8, 81.4, 81.1, 77.2,
64.4, 58.5, 34.6, 34.4, 31.9, 28.7, 27.4, 27.1, 24.5, 23.2, 16.6, 16.4;
MS (FAB) m/z 300 (M + H+), 244, 200, 186, 154; HRMS calcd
for C15H25NO5 (M + H+) 300.1810, found 300.1806.
(1S,2′S,4′R)-[2-Hydroxy-1-(4-methyl-5-oxo-tetrahydro-furan-
2-yl)-ethyl]-carbamic Acid tert-Butyl Ester (8). To a stirred
solution of 7 (0.67 g, 2.2 mmol) in THF-H2O (1/1, 26 mL) was
added p-toluenesulfonic acid (0.85 g, 4.4 mmol). The mixture was
stirred at room temperature for 2 days, saturated NaHCO3 solution
was added to pH 8, the mixture was extracted with AcOEt (3 × 60
mL), and the combined organic layers were washed with brine,
dried over Na2SO4, and concentrated. The residue was purified by
flash chromatography (hexane/AcOEt 1/2) to give 8 (0.43 g,
75%): [R]D +4.6 (c 0.85, CHCl3); 1H NMR (CDCl3, 400 MHz) δ
4.92 (d, 1H, J ) 8.2 Hz), 4.78 (b, 1H), 3.80-3.69 (m, 3H), 2.73
(m, 1H), 2.41 (m, 1H), 1.99 (m, 1H), s, 3H), 1.45 (s, 9H), 1.29 (d,
3H, J ) 7.4 Hz); 13C NMR (CDCl3, 100 MHz) δ 180.5, 156.5,
80.8, 78.2, 63.5, 54.9, 34.6, 32.7, 28.7, 16.9; MS (FAB) m/z 260
(M + H+), 204, 160, 136; HRMS calcd for C12H21NO5 (M + H+)
260.1511, found 260.1506.
1
314.1613. For 3: [R]D -68.8 (c 1.29, CHCl3); H NMR (CDCl3,
400 MHz, 50 °C) δ 5.44 (b, 1H), 4.57 (b, 1H), 4.08 (b, 1H), 4.07-
3.82 (m, 2H), 3.72 (s, 3H), 1.56 (s, 3H), 1.47 (s, 12H); 13C NMR
(CDCl3, 100 MHz) δ 154.8, 153.9, 95.6, 85.8, 82.3, 77.7, 65.3,
64.8, 62.6, 53.1, 28.6, 26.1, 25.5; MS (FAB) m/z 314 (M + H+),
258, 240, 214, 200; HRMS calcd for C15H23NO6 (M + H+)
314.1617, found 314.1613.
(4S,1′S)-4-(1-Hydroxy-3-methoxycarbonyl-propyl)-2,2-dimethyl-
oxazolidine-3-carboxylic Acid tert-Butyl Ester (4). In procedure
1, a mixture of 2 (0.82 g, 2.6 mmol) and palladium (5% on barium
sulfate, 0.25 g) in AcOEt (10 mL) was charged with H2 to 50 psi
and stirred for 3 h, then filtered through a pad of Celite and washed
with AcOEt. The combined filtrate was concentrated to give product
4 (0.78 g, 95%). In procedure 2, into a solution of 5 (0.71 g, 2.3
mmol) in MeOH (20 mL) was added NaBH4 (0.18 g, 4.6 mmol)
portionwise at -15 °C. The mixture was stirred at -15 to 0 °C for
5 h, saturated NH4Cl (5 mL) was added, MeOH was removed, the
aqueous solution was extracted with AcOEt, and the organic layer
was dried and concentrated. Flash chromatography (hexane/AcOEt
2/1) of the residue gave 4 (0.6 g, 85%): [R]D -50.3 (c 0.64, CHCl3);
1H NMR (CDCl3, 400 MHz) δ 4.14 (m, 1H), 4.09 (m, 1H), 3.98
(m, 1H), 3.94 (m, 1H), 3.80 (m, 1H), 3.65 (s, 3H), 2.52-2.42 (m,
2H), 1.82 (m, 1H), 1.62 (m, 1H), 1.56 (s, 3H), 1.47 (s, 12H); 13C
NMR (CDCl3, 100 MHz) δ 174.5, 154.6, 94.8, 82.2, 77.6, 72.3,
65.1, 62.1, 51.9, 30.9, 28.7, 26.8, 24.5; MS (FAB) m/z 318 (M +
H+).
(4S)-4-(3-Methoxycarbonyl-propionyl)-2,2-dimethyl-oxazoli-
dine-3-carboxylic Acid tert-Butyl Ester (5). Into a solution of
Dess-Martin periodinane reagent (5 g, 12 mmol) in CH2Cl2 (50
mL), 3 (2.7 g, 8.6 mmol) in CH2Cl2 (25 mL) was added. The
mixture was stirred at room temperature for 3 h, saturated NaHCO3
and Na2SO3 were added, and then 1 N NaOH was added to get a
clear solution. The aqueous layer was extracted with CH2Cl2 (2 ×
50 mL); the combined organic layers were dried over Na2SO4 and
concentrated. Flash chromatography (hexane/AcOEt 5/1) of the
residue gave the ketone (2.0 g, 75%). A mixture of the ketone (0.41
g, 1.3 mmol) and palladium (5% on barium sulfate, 0.1 g) in AcOEt
(6 mL) was charged with H2 to 50 psi and stirred for 3 h, then
filtered through a pad of Celite and washed with AcOEt. The
combined filtrate was concentrated to give 5 (0.4 g, 96%): 1H NMR
(CDCl3, 400 MHz) δ 4.31 (b, 1H), 4.13-3.96 (m, 2H), 3.64 (s,
3H), 2.78 (m, 2H), 2.58 (m, 2H), 1.67 (s, 3H), 1.45 (s, 9H), 1.38
(s, 3H); 13C NMR (CDCl3, 100 MHz) δ 206.4, 172.7, 152.3, 94.4,
80.6, 76.9, 65.1, 51.7, 33.7, 33.3, 28.1, 25.3, 24.6; MS (FAB) m/z
316 (M + H+), 260, 216, 202.
(1S,2′S,4′R)-[2-Allyloxy-1-(4-methyl-5-oxo-tetrahydro-furan-
2-yl)-ethyl]-carbamic Acid tert-Butyl Ester (9). Into a solution
of 8 (0.2 g, 0.77 mmol) in CH2Cl2 (5 mL) and cyclohexane (10
mL) was added 2,2,2-trichloro-acetimidic acid allyl ester (0.33 g,
1.54 mmol) dropwise at 0 °C, followed by trifluoromethanesulfonic
acid (12 µL). The mixture was warmed to room temperature and
stirred for 5 h. The precipitate was filtered off, and the filtrate was
washed with saturated NaHCO3 and brine, dried over Na2SO4, and
concentrated. Flash chromatography (hexane/AcOEt 2/1) of the
residue gave 9 (0.18 g, 80%): [R]D +7.8 (c 0.85, CHCl3); 1H NMR
(CDCl3, 400 MHz) δ 5.95 (b, 1H), 5.90 (m, 1H), 5.25 (m, 2H), 4.8
(m, 1H), 4.63 (m, 1H), 4.0 (m, 1H), 3.5 (m, 2H), 2.74 (m, 1H),
2.39 (m, 1H), 1.96 (m, 1H), 1.45 (s, 9H), 1.30 (d, 3H, J ) 7.4 Hz);
13C NMR (CDCl3, 100 MHz) δ 180.4, 156.7, 134.5, 117.9, 81.0,
80.7, 72.6, 69.6, 66.4, 34.8, 32.5, 28.7, 16.9; MS (FAB) m/z 300
(M + H+), 244, 200, 154; HRMS calcd for C15H25NO5 (M + H+)
300.1810, found 300.1816.
(1S,2S,4R)-(1-Allyloxymethyl-4-butylcarbamoyl-2-hydroxy-
pentyl)-carbamic Acid tert-Butyl Ester (10). A mixture of 9 (0.26
g, 86 µmol) and butylamine (1.8 mL) was stirred at room
temperature for 4 h. Excess butylamine was removed under reduced
pressure. The residue was purified by flash chromatography
(hexane/AcOEt 2/1) to give 10 (0.13 g, 40%): [R]D -14 (c 0.25,
1
(4S,2′S)-2,2-Dimethyl-4-(5-oxo-tetrahydro-furan-2-yl)-oxazol-
idine-3-carboxylic Acid tert-Butyl Ester (6). Compound 4 (0.32
g, 1 mmol) was dissolved in toluene (5 mL), acetic acid (18 µL)
CHCl3); H NMR (CDCl3, 400 MHz) δ 5.86 (m, 2H), 5.20 (m,
3H), 3.98 (m, 2H), 3.91 (m, 1H), 3.65 (m, 2H), 3.62 (m, 2H), 3.24
(m, 2H), 2.49 (m, 1H), 1.65 (m, 2H), 1.45 (s, 9H), 1.48-1.32 (m,

4554 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
4H), 1.16 (d, 3H, J ) 7.0 Hz), 0.92 (t, 3H, J ) 7.2 Hz); 13C NMR
(CDCl3, 100 MHz) δ 176.8, 156.7, 134.3, 118.0, 80.0, 77.6, 73.3,
72.9, 70.6, 53.4, 39.5, 38.5, 37.7, 32.1, 28.8, 20.5, 14.2; MS (FAB)
m/z 373 (M + H+), 273, 200, 154; HRMS calcd for C19H36N2O5
(M + H+) 373.2702, found 373.2690.
39.6, 38.5, 37.7, 33.2, 31.9, 28.7, 20.5, 18.1, 14.2; MS (FAB) m/z
587 (M + H+), 513, 414, 154; HRMS calcd for C28H50N4O7S (M
+ H+) 587.3492, found 587.3495.
(2R,4S,5S,2′S,2′′S)-5-[2-(2-Acetylamino-3-allylsulfanyl-propio-
nylamino)-propionylamino]-6-allyloxy-4-hydroxy-2-methyl-hex-
anoic Acid Butylamide (14). Into a solution of 11 (74 mg, 0.16
mmol) in CH2Cl2 (2.4 mL) was added TFA (0.4 mL). The mixture
was stirred at room temperature for 30 min and then concentrated
in a vacuum. The residue was treated with AcOEt (10 mL), washed
with 1 N NaHCO3, dried, and concentrated in a vacuum. The residue
was dissolved in CH2Cl2-H2O (1/1, 6 mL) and cooled to 0 °C.
N-Ac S-allyl cysteine (49 mg, 0.32 mmol) and 1-hydroxybenzot-
riazole (HOBt) (33 mg, 0.32 mmol), followed by 1-ethyl-3-(3-
dimethylaminopropyl)carbodiimide hydrochloride (EDCI; 46 mg,
0.32 mmol), were added. The mixture was stirred at 0-5 °C for 2
days, and then diluted with AcOEt (5 mL). 1 N HCl was added to
pH 5, and the mixture was extracted with AcOEt (3 × 10 mL),
then processed as described above. Flash chromatography (8%
MeOH in AcOEt) of the residue gave 14 (23 mg, 27%): [R]D -31.2
(1S,1′S,2′S,4′R)-[1-(1-Allyloxymethyl-4-butylcarbamoyl-2-hy-
droxy-pentylcarbamoyl)-ethyl]-carbamic Acid tert-Butyl Ester
(11). Into a solution of 10 (0.17 g, 0.46 mmol) in CH2Cl2 (6 mL)
was added TFA (1 mL). The solution was stirred at room
temperature for 30 min and then concentrated. The residue was
dissolved in CH2Cl2 (10 mL) and cooled to 0 °C, and N-Boc alanine
(0.14 g, 0.7 mmol), PyBOP (0.36 g, 0.7 mmol), and diisopropyl-
ethylamine (DIEA) (0.32 mL, 1.85 mmol) were added consecu-
tively. The mixture was stirred at 0 °C to room temperature for 2
h and concentrated, and the residue was treated with 10% citric
acid (2 mL), then extracted with AcOEt (3 × 20 mL). The combined
organic layers were washed with saturated NaHCO3, brine, dried
over Na2SO4, and concentrated. Flash chromatography (AcOEt) of
the residue gave 11 (0.17 g, 85%): [R]D -25.1 (c 0.55, MeOH);
1H NMR (CDCl3, 400 MHz) δ 6.67 (d, 1H, J ) 8.8 Hz), 5.9-5.82
(m, 2H), 5.28-5.19 (m, 2H), 4.92 (b, 1H), 4.13 (b, 1H), 3.99-
3.92 (m, 4H), 3.62 (d, 2H, J ) 4.0 Hz), 3.24 (dd, 2H, J ) 12.9,
6.7 Hz), 2.48 (m, 1H), 1.66 (m, 2H), 1.55 (m, 2H), 1.45 (s, 9H),
1.38 (d, 3H, J ) 7.1 HZ), 1.35 (m, 2H), 1.15 (d, 3H, J ) 7.0 Hz),
0.93 (t, 3H, J ) 7.3 Hz); 13C NMR (CDCl3, 100 MHz) δ 176.8,
173.4, 154.7, 134.3, 118.2, 80.5, 77.6, 72.9, 72.5, 70.1, 52.4, 39.6,
38.4, 37.8, 32.1, 28.7, 20.5, 19.1, 17.9, 14.2; MS (FAB) m/z 444
(M + H+), 370, 326, 307, 154; HRMS calcd for C22H41N3O6 (M
+ H+) 444.3087, found 444.3084.
1
(c 0.5, MeOH); H NMR (MeOD, 400 MHz) δ 7.48 (d, 1H, J )
8.8 Hz), 5.91-5.76 (m, 2H), 5.29-5.10 (m, 4H), 4.44 (m, 1H),
4.36 (m, 1H), 3.98 (m, 3H), 3.74 (m, 1H), 3.53 (m, 1H), 3.45 (m,
1H), 3.19 (m, 4H), 2.86 (m, 1H), 2.71 (m, 1H), 2.56 (b, 1H), 2.0
(s, 3H), 1.86 (m, 1H), 1.69 (m, 1H), 1.48 (m, 2H), 1.38 (d, 3H, J
) 7.0 Hz), 1.33 (m, 2H), 1.11 (d, 3H, J ) 6.8 Hz), 0.94 (t, 3H, J
) 7.2 Hz); 13C NMR (MeOD, 100 MHz) δ 177.9, 173.8, 172.5,
171.8, 135.1, 134.3, 117.1, 116.2, 71.9, 69.4, 67.8, 53.5, 49.8, 49.6,
39.1, 38.1, 37.6, 34.4, 32.0, 21.4, 20.1, 17.8, 17.1, 13.2; MS (FAB)
m/z 529 (M + H+), 511, 307, 154; HRMS calcd for C25H44N4O6S
(M + H+) 529.3069, found 529.3066.
(1S,1′S,1′′S,2′′S,4′′R)-{2-Allyloxy-1-[1-(1-allyloxymethyl-4-bu-
tylcarbamoyl-2-hydroxy-pentylcarbamoyl)-ethylcarbamoyl]-eth-
yl}-carbamic Acid tert-Butyl Ester (12). Into a solution of 11
(33 mg, 0.074 mmol) in CH2Cl2 (2.0 mL) was added TFA (0.33
mL). The mixture was stirred for 30 min and then concentrated in
a vacuum. The amine salt was dissolved in CH2Cl2 (4 mL) and
cooled to 0 °C, and N-Boc O-allyl serine (37 mg, 0.15 mmol) and
PyBOP (77 mg, 0.15 mmol), followed by DIEA (70 µL, 0.37
mmol), were added. The mixture was stirred at 0 °C to room
temperature for 2 h, then processed as described above. Flash
chromatography (4% MeOH in AcOEt) of the residue gave pure
(3S,6S,9S,1′S,3′R)-[3-(3-Butylcarbamoyl-1-hydroxy-butyl)-6-
methyl-5,8-dioxo-1,11-dioxa-4,7-diaza-cyclopentadec-13-en-9-
yl]-carbamic Acid tert-Butyl Ester (15). Into a solution of 12 (25
mg, 0.044 mmol) in CH2Cl2 (18 mL) was added a solution of second
generation Grubbs catalyst14 (4 mg, 4.5 µmol) in CH2Cl2 (4 mL).
The mixture was stirred at room temperature overnight and then
concentrated. The residue was purified by flash chromatography
(4% MeOH in AcOEt) to give 15 (8 mg, 34%): [R]D -29 (c 0.4,
1
MeOH); H NMR (MeOD, 400 MHz) δ 5.65 (m, 2H), 4.61 (m,
1H), 4.27 (m, 1H), 4.02-3.90 (m, 5H), 3.69-3.50 (m, 5H), 3.18-
3.13 (m, 2H), 2.59 (m, 1H), 1.98-1.71 (m, 5H), 1.44 (s, 9H), 1.34
(d, 3H, J ) 6.8 Hz), 1.36 (m, 2H), 1.12 (d, 3H, J ) 7.0 Hz), 0.94
(t, 3H, J ) 7.2 Hz); 13C NMR (MeOD, 100 MHz) δ 176.4, 172.1,
170.8, 155.1, 127.5, 126.6, 79.2, 68.3, 68.1, 67.8, 67.2, 52.6, 52.0,
47.8, 37.5, 36.6, 36.0, 33.8, 30.1, 26.1, 25.2, 24.6, 18.5, 11.6; MS
(FAB) m/z 543 (M + H+), 469, 425, 297, 154; HRMS calcd for
C26H46N4O8 (M + H+) 543.3394, found 543.3396; LC/MS retention
time [A] 5.15 min, [B] 7.20 min.
1
12 (28 mg, 67%): [R]D -21 (c 1.3, MeOH); H NMR (CDCl3,
400 MHz) δ 7.0 (d, 1H, J ) 4.8 Hz), 6.67 (b, 1H), 6.1 (b, 1H),
5.85 (m, 2H), 5.49 (d, 1H, J ) 5.6 Hz), 5.28-5.16 (m, 4H), 4.36
(b, 1H), 3.98-3.81 (m, 6H), 3.55 (m, 3H), 3.22 (m, 4H), 2.50 (m,
1H), 1.60 (m, 3H), 1.45 (s, 9H), 1.41 (d, 3H, J ) 7.0 Hz), 1.35 (m,
2H), 1.14 (d, 3H, J ) 7.0 Hz), 0.91 (t, 3H, J ) 7.2 Hz); 13C NMR
(CDCl3, 100 MHz) δ 176.8, 172.7, 170.5, 156.1, 134.5, 134.3,
118.1, 117.9, 81.0, 72.7, 72.5, 69.8, 54.7, 52.3, 46.8, 39.5, 38.5,
37.7, 32.1, 28.7, 27.7, 26.7, 20.5, 19.1, 14.2; MS (FAB) m/z 593
(M + Na+), 571 (M + H+); HRMS calcd for C28H50N4O8 (M +
H+) 571.3693, found 571.3699.
(3S,6S,9S,1′S,3′R)-[3-(3-Butylcarbamoyl-1-hydroxy-butyl)-6-
methyl-5,8-dioxo-1,11-dioxa-4,7-diaza-cyclopentadec-9-yl]-car-
bamic Acid tert-Butyl Ester (16). A mixture of 15 (9 mg, 0.016
mmol) and 10% Pd/C (16 mg) in AcOEt (2 mL) was charged with
H2 (balloon) and stirred overnight. The suspension was filtered
through a pad of Celite washed with AcOEt, the combined filtrate
was concentrated, and the residue was purified by flash chroma-
tography (8% MeOH in AcOEt) to give 16 (8.2 mg, 91%): [R]D
(1S,1′S,1′′S,2′′S,4′′R)-{1-[1-(1-Allyloxymethyl-4-butylcarbam-
oyl-2-hydroxy-pentylcarbamoyl)-ethylcarbamoyl]-2-allylsulfa-
nyl-ethyl}-carbamic Acid tert-Butyl Ester (13). Into a solution
of 11 (120 mg, 0.27 mmol) in CH2Cl2 (6.0 mL) was added TFA
(1.0 mL). The mixture was stirred at room temperature for 30 min
and then concentrated in a vacuum. The amine salt was dissolved
in CH2Cl2 (7 mL) and cooled to 0 °C, and N-Boc S-allyl cysteine
(130 mg, 0.0.47 mmol) and PyBOP (0.21 g, 0.45 mmol), followed
by DIEA (230 µL, 1.35 mmol), were added. The mixture was
processed as described above. Flash chromatography (2% MeOH
in AcOEt) of the residue gave pure 13 (0.12 g, 75%): [R]D -62.7
(c 0.4, MeOH); 1H NMR (CDCl3, 400 MHz) δ 7.0 (d, 1H, J ) 8.0
Hz), 6.85 (b, 1H), 6.08 (b, 1H), 5.86-5.73 (m, 2H), 5.45 (s, 1H),
5.26-5.12 (m, 4H), 4.52 (m, 1H), 4.24 (m, 1H), 4.0-3.92 (m, 4H),
3.59 (d, 2H, J ) 4.6 Hz), 3.23 (dd, 2H, J ) 13.0, 6.9), 3.15 (d,
2H, J ) 7.2 Hz), 2.83 (m, 2H), 2.57 (m, 1H), 1.68-1.50 (m, 2H),
1.48-1.41 (m, 2H), 1.46 (s, 9H), 1.42 (d, 3H, J ) 7.0 Hz), 1.35
(m, 2H), 1.14 (d, 3H, J ) 7.0 Hz), 0.92 (t, 3H, J ) 7.3 Hz); 13C
NMR (CDCl3, 100 MHz) δ 177.6, 172.6, 170.9, 156.2, 134.5, 134.0,
118.6, 117.9, 81.2, 80.2, 72.7, 71.9, 70.0, 55.9, 54.3, 49.9, 49.1,
1
-38.5 (c 0.4, MeOH); H NMR (MeOD, 400 MHz) δ 4.64 (m,
1H), 4.39 (m, 1H), 4.24 (m, 1H), 4.01 (m, 1H), 3.64-3.39 (m,
7H), 3.16 (m, 2H), 2.58 (m, 2H), 2.02-1.86 (m, 3H), 1.73 (m,
2H), 1.60 (m, 2H), 1.45 (s, 9H), 1.46-1.32 (m, 6H), 1.34 (d, 3H,
J ) 6.9 Hz), 1.36 (m, 2H), 1.12 (d, 3H, J ) 6.8 Hz), 0.94 (t, 3H,
J ) 7.2 Hz); 13C NMR (MeOD, 100 MHz) δ 176.3, 172.1, 170.1,
154.9, 78.2, 69.8, 69.3, 69.0, 68.0, 67.6, 52.6, 52.1, 37.5, 363, 36.0,
26.1, 25.3, 25.1, 24.5, 18.5, 16.4, 15.7, 11.6; MS (FAB) m/z 545
(M + H+), 3.7, 289, 154; HRMS calcd for C26H48N4O8 (M + H+)
545.3550, found 545.3546; LC/MS retention time [A] 5.23 min,
[B] 7.39 min.
(3S,6S,9S,1′S,3′R)-[3-(3-Butylcarbamoyl-1-hydroxy-butyl)-6-
methyl-5,8-dioxo-1-oxa-11-thia-4,7-diaza-cyclopentadec-13-en-
9-yl]-carbamic Acid tert-Butyl Ester (17). Into a solution of 13
(16 mg, 0.023 mmol) in CH2Cl2 (12 mL) was added second

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4555
generation Grubbs catalyst14 (4 mg, 4.5 µmol). The mixture was
stirred at room temperature overnight, additional catalyst (2 mg,
2.25 µmol) was added, and the mixture was stirred for 6 h. A few
drops of MeOH was added, the mixture was concentrated, and the
residue was purified by flash chromatography (4% MeOH in
AcOEt) to give 17 (3.1 mg, 25%): [R]D -58.5 (c 0.4, MeOH); 1H
NMR (CDCl3, 400 MHz) δ 5.68 (m, 1H), 5.55 (m, 1H), 4.57 (m,
1H), 4.0 (m, 1H), 3.99-3.89 (m, 3H), 3.63-3.55 (m, 3H), 3.22-
3.11 (m, 4H), 2.85 (m, 2H), 2.62 (m, 2H), 1.76 (m, 2H), 1.48-
1.35 (m, 2H), 1.46 (s, 9H), 1.34 (d, 3H, J ) 7.0 Hz), 1.12 (d, 3H,
J ) 7.0 Hz), 0.94 (t, 3H, J ) 7.3 Hz); 13C NMR (CDCl3, 100
MHz) δ 177.9, 173.0, 172.7, 156.8, 130.5, 129.5, 79.6, 70.4, 70.2,
69.0, 54.1, 54.0, 50.7, 39.0, 38.0, 37.6, 32.5, 31.6, 27.7, 26.5, 20.1,
18.0, 13.2; MS (FAB) m/z 559 (M + H+), 485, 307, 154; HRMS
calcd for C26H46N4O7S (M + H+) 559.3165, found 559.3166; LC/
MS retention time [A] 19.43 min, [B] 27.15 min.
(3S,6S,9S,1′S,3′R)-4-(9-Acetylamino-6-methyl-5,8-dioxo-1-
oxa-11-thia-4,7-diaza-cyclopentadec-13-en-3-yl)-N-butyl-4-hy-
droxy-2-methyl-butyramide (18). Into a solution of 14 (21 mg,
0.04 mmol) in CH2Cl2 (20 mL) was added second generation
Grubbs catalyst14 (7 mg, 8 µmol). The mixture was stirred at room
temperature overnight, additional catalyst (3.5 mg, 4 µmol) was
added, and the mixture was stirred for 6 h. A few drops of MeOH
was added, and the mixture was concentrated. The residue was flash
purified by flash chromatography (10% MeOH in AcOEt) to give
18 (4.5 mg, 23%): 1H NMR (MeOD, 400 MHz) δ 7.84 (b, 1H),
7.2 (d, 1H, J ) 8.4 Hz), 5.65 (m, 1H), 5.56 (m, 1H), 4.55 (m, 1H),
4.36 (m, 1H), 3.97-3.90 (m, 3H), 3.60-3.54 (m, 3H), 3.21-2.87
(m, 3H), 2.66 (m, 1H), 2.59 (m, 3H), 2.02 (m, 1H), 2.0 (s, 3H),
1.74 (m, 1H), 1.48-1.32 (m, 8H), 1.12 (d, 3H, J ) 6.9 Hz), 0.94
(t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 125 MHz) δ 177.6, 172.7,
172.1, 171.8, 130.4, 128.9, 70.1, 69.9, 68.7, 60.2, 53.6, 52.7, 48.5,
38.7, 37.6, 31.8, 31.3, 29.4, 20.9, 19.7, 17.6, 15.4, 13.1; MS (FAB)
m/z 501 (M + H+); HRMS calcd for C23H40N4O6S (M + H)+
500.2741, found 500.2734; LC/MS retention time [A] 3.98 min,
[B] 6.51 min.
13C NMR (CDCl3, 100 MHz) δ 177.5, 156.7, 138.7, 129.5, 128.9,
127.4, 79.9, 68.4, 54.1, 39.7, 38.6, 38.2, 36.7, 34.2, 32.1, 28.8, 20.5,
17.5, 14.2; MS (FAB) m/z 439 (M + H+), 339, 230, 172, 154;
HRMS calcd for C23H38N2O4S (M + H+) 439.2637, found
439.2642.
(1S,1′S,2′S,4′R)-[1-(1-Benzylsulfanylmethyl-4-butylcarbamoyl-
2-hydroxy-pentylcarbamoyl)-ethyl]-carbamic Acid tert-Butyl
Ester (21). Into a solution of 20 (0.084 g, 0.19 mmol) in CH2Cl2
(3 mL) was added TFA (0.5 mL). The mixture was stirred at room
temperature for 30 min and then concentrated in a vacuum. The
residue was dissolved in CH2Cl2 (5 mL) and cooled to 0 °C. N-Boc
alanine (0.079 g, 0.38 mmol), PyBOP (0.21 g, 0.38 mmol), and
DIEA (0.18 mL, 0.9 mmol) were added consecutively. The mixture
was stirred at 0 °C to room temperature for 3 h and then
concentrated. The residue was treated with 10% citric acid (2 mL)
and extracted with AcOEt (3 × 20 mL); the combined organic
layers were washed with saturated NaHCO3 and brine, dried over
Na2SO4, and concentrated. Flash chromatography (AcOEt/hexane
4/1) of the residue gave pure 21 (88 mg, 90%): [R]D -53.1 (c
0.96, MeOH); 1H NMR (CDCl3, 400 MHz) δ 7.30-7.20 (m, 5H),
6.80 (d, 1H, J ) 8.6 Hz), 6.41 (bs, 1H), 5.26 (bs, 1H), 4.12 (m,
1H), 3.88 (m, 2H), 3.70 (s, 2H), 3.23-3.13 (m, 2H), 2.64-2.51
(m, 3H), 1.57 (m, 2H), 1.46-1.29 (m, 5H), 1.40 (s, 9H), 1.36 (d,
3H, J ) 7.1 Hz), 1.13 (d, 3H, J ) 6.9 Hz), 0.90 (t, 3H, J ) 7.3
Hz); 13C NMR (CDCl3, 100 MHz) δ 177.6, 174.0, 155.7, 138.6,
129.4, 128.9, 127.4, 80.6, 68.5, 60.9, 52.6, 51.2, 39.8, 38.6, 38.0,
36.7, 33.8, 31.9, 28.7, 20.5, 17.6, 14.6, 14.2; MS (FAB) m/z 510
(M + H+), 492, 436, 392, 307, 154; HRMS calcd for C26H43N3O5S
(M + H+) 510.2975, found 510.2979.
(1S,1′S,1′′S,2′′S,4′′R)-{2-Benzylsulfanyl-1-[1-(1-benzylsulfa-
nylmethyl-4-butylcarbamoyl-2-hydroxy-pentylcarbamoyl)-eth-
ylcarbamoyl]-ethyl}-carbamic Acid tert-Butyl Ester (22). Into
a solution of 21 (0.09 g, 0.176 mmol) in CH2Cl2 (3 mL) was added
TFA (0.5 mL). The mixture was stirred at room temperature for
30 min and then concentrated in a vacuum. The residue was
dissolved in CH2Cl2 (5 mL) and cooled to 0 °C. N-Boc S-benzyl
cysteine (0.1 g, 0.36 mmol), PyBOP (0.19 g, 0.36 mmol), and DIEA
(0.17 mL, 0.82 mmol) were added consecutively. The mixture was
stirred at 0 °C to room temperature for 3 h and concentrated, the
residue was treated with 10% citric acid (2 mL) and extracted with
AcOEt (3 × 20 mL), and the combined organic layers were washed
with saturated NaHCO3 and brine, dried over Na2SO4, and
concentrated. Flash chromatography (AcOEt) of the residue gave
22 (70 mg, 57%): [R]D -31.8 (c 0.76, MeOH); 1H NMR (MeOD,
400 MHz) δ 7.34-7.19 (m, 10H), 4.27 (m, 1H), 4.18 (m, 1H),
3.95 (m, 1H), 3.76 (s, 2H), 3.72 (m, 1H), 3.69 (s, 2H), 3.16 (m,
2H), 2.83 (m, 1H), 2.64-2.48 (m, 4H), 1.49 (m, 2H), 1.47-1.32
(m, 6H), 1.45 (s, 9H), 1.40 (d, 3H, J ) 7.1 Hz), 1.10 (d, 3H, J )
7.0 Hz), 0.92 (t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz) δ
178.0, 177.8, 172.3, 156.1, 138.7, 138.5, 129.2, 128.5, 127.4, 126.9,
126.3, 79.9, 68.9, 54.3, 52.9, 49.9, 39.2, 39.1, 38.3, 37.7, 37.6, 36.0,
35.7, 33.4, 32.6, 31.6, 27.7, 20.1, 17.7, 17.3, 13.2; MS (FAB) m/z
704 (M + H+), 629, 307, 154; HRMS calcd for C36H54N4O6S2 (M
+ H+) 703.3556, found 703.3555.
(1S,2′S,4′R)-[2-Benzylsulfanyl-1-(4-methyl-5-oxo-tetrahydro-
furan-2-yl)-ethyl]-carbamic Acid tert-Butyl Ester (19). Into a
solution of 8 (0.2 g, 0.77 mmol) in CH2Cl2 (12 mL) were added
imidazole (0.11 g, 1.5 mmol), 1,1′-(azodicarbonyl)dipiperidine
(ADDP) (0.39 g, 1.5 mmol), and benzyl mercaptan (0.4 mL, 3.0
mmol), followed by PMe3 (1 M in toluene, 1.54 mL) dropwise.
The mixture was stirred at room temperature for 1 day, hexane (12
mL) was added, and the precipitate was removed by filtration. The
filtrate was concentrated, and the residue was purified by flash
chromatography (hexane/AcOEt 3/1) to give the product 19 (0.19
1
g, 66%): [R]D +9.2 (c 0.9, CHCl3); H NMR (CDCl3, 400 MHz)
δ 7.33-7.23 (m, 5H), 4.77 (t, 1H, J ) 6.6 Hz), 4.69 (d, 1H, J )
12.3), 3.87(dd, 1H, J ) 16.3, 8.1 Hz), 3.73 (s, 2H), 2.70 (dd, 1H,
J ) 9.5, 7.1 Hz), 2.58 (m, 2H), 2.36 (m, 1H), 1.92 (m, 1H), 1.45
(s, 9H), 1.26 (d, 3H, J ) 7.4 Hz); 13C NMR (CDCl3, 100 MHz) δ
180.5, 156.4, 138.1, 129.5, 128.9, 127.6, 80.6, 78.1, 52.8, 36.4,
34.8, 33.9, 32.7, 28.7, 16.9; MS (FAB) m/z 366 (M + H+), 310,
266, 186; HRMS calcd for C19H27NO4S (M) 364.1569, found
364.1563.
(3S,6S,9S,1′S,3′R)-[3-(3-Butylcarbamoyl-1-hydroxy-butyl)-6-
methyl-5,8-dioxo-1,11-dithia-4,7-diaza-cyclopentadec-9-yl]-car-
bamic Acid tert-Butyl Ester (23). Into a solution of 22 (42 mg,
0.06 mmol) in liquid ammonia (300 mL) was added sodium until
a blue color persisted for about 10 min. 1,4-Dibromobutane (0.016
mL, 0.12 mmol) was added, and the mixture was warmed at reflux
for 2 h. Ammonia was removed under a stream of argon; the residue
was dissolved in AcOEt, washed with 10% citric acid, saturated
NaHCO3, and brine, dried over Na2SO4, and concentrated. Flash
chromatography of the residue gave pure 23 (13 mg, 38%): [R]D
(1S,2S,4R)-(1-Benzylsulfanylmethyl-4-butylcarbamoyl-2-hy-
droxy-pentyl)-carbamic Acid tert-Butyl Ester (20). Trimethyl
aluminum (1.0 M in toluene, 0.22 mL) was added to a solution of
butylamine (0.088 mL, 0.88 mmol) in CH2Cl2 (2.5 mL) and stirred
for 15 min. A solution of 19 (82 mg, 0.22 mmol) in CH2Cl2 (2.5
mL) was added, and the stirring was continued for 15 min. The
mixture was heated to 45 °C until TLC indicated completion of
reaction. After cooling, 5% HCl was added, and the clear solution
was extracted with CH2Cl2 (3 × 20 mL); the combined organic
layers were washed with saturated NaHCO3 and brine, dried, and
concentrated. Flash chromatography (hexane/AcOEt 1/1) of the
residue gave pure 20 (85 mg, 88%): [R]D +3.3 (c 0.4, CHCl3); 1H
NMR (CDCl3, 400 MHz) δ 7.34-7.23 (m, 5H), 6.04 (b, 1H), 5.04
(d, 1H, J ) 9.2 Hz), 3.88 (m, 1H), 3.73 (s, 2H), 3.59 (m, 1H), 3.22
(m, 2H), 2.60 (m, 3H), 1.68 (m, 1H), 1.48 (m, 3H), 1.45 (s, 9H),
1.34 (m, 2H), 1.20 (d, 3H, J ) 7.0 Hz), 0.91 (t, 3H, J ) 7.3 Hz);
1
-17.5 (c 0.4, MeOH); H NMR (MeOD, 400 MHz) δ 4.55 (m,
1H), 4.36 (bs, 1H), 3.99 (m, 1H), 3.54 (d, 1H, J ) 9.9 Hz), 3.18
(m, 4H), 2.91-2.81 (m, 3H), 2.62-2.53 (m, 6H), 1.91 (m, 2H),
1.71 (m, 4H), 1.45 (s, 9H), 1.42 (m, 2H), 1.38 (d, 3H, J ) 7.0 Hz),
1.12 (d, 3H, J ) 7.0 Hz), 0.94 (t, 3H, J ) 7.2 Hz); 13C NMR
(MeOD, 100 MHz) δ 178.0, 174.1, 171.5, 156.8, 80.1, 70.4, 62.4,
61.1, 54.3, 53.6, 39.0, 38.0, 37.8, 35.2, 31.6, 31.6, 30.6, 29.8, 27.9,

4556 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
27.6, 20.1, 17.9, 13.2; MS (FAB) m/z 577 (M + H+), 503, 307,
154; HRMS calcd for C26H48N4O6S2 (M + H+) 577.3105, found
577.3106; LC/MS retention time [A] 19.94 min, [B] 7.84 min.
(3S,6S,9S,1′S,3′R)-[3-(3-Butylcarbamoyl-1-hydroxy-butyl)-6-
methyl-5,8-dioxo-1,11-dithia-4,7-diaza-cyclohexadec-9-yl]-car-
bamic Acid tert-Butyl Ester (24). Compound 24 (14 mg, 46%)
was prepared from 22 (36 mg, 0.051 mmol) and 1,5-dibromopentane
(0.017 mL, 0.1 mmol) according to the general procedure for the
preparation of 23: [R]D -31.8 (c 0.68, MeOH); 1H NMR (MeOD,
400 MHz) δ 4.48 (m, 1H), 4.28 (m, 1H), 3.97 (m, 1H), 3.66 (m,
1H), 3.23-3.15 (m, 4H), 2.88-2.75 (m, 3H), 2.66-2.45 (m, 6H),
1.72-1.60 (m, 4H), 1.49-1.35 (m, 6H), 1.45 (s, 9H), 1.38 (d, 3H,
J ) 7.0 Hz), 1.12 (d, 3H, J ) 7.0 Hz), 0.94 (t, 3H, J ) 7.2 Hz);
13C NMR (MeOD, 100 MHz) δ 177.9, 173.6, 171.7, 156.2, 79.8,
69.3, 57.8, 53.9, 53.1, 49.3, 46.5, 46.4, 39.0, 37.8, 34.4, 31.6, 28.1,
27.9, 27.6, 26.8, 26.4, 26.3, 20.1, 13.2; MS (FAB) m/z 591 (M +
H+), 563,542; HRMS calcd for C27H50N4O6S2 (M + H+) 591.3257,
found 591.3257; LC/MS retention time [A] 22.80 min, [B] 8.11
min.
9-yl]-carbamic Acid tert-Butyl Ester (28). Compound 28 (10 mg,
30%) was prepared from 22 (42 mg, 0.06 mmol) and trans-1,4-
dibromo-2-butene (30 mg, 0.14 mmol) according to the general
procedure for the preparation of 23: [R]D -42.5 (c 0.24, MeOH);
1H NMR (MeOD, 400 MHz) δ 6.74 (d, 1H, J ) 7.3 Hz), 5.55 (m,
2H), 4.50 (dd, 1H, J ) 14.6, 7.5 Hz), 4.28 (m, 1H), 3.80 (m, 1H),
3.67 (m, 2H), 3.20-3.06 (m, 5H), 2.89-2.77 (m, 3H), 2.56 (m,
1H), 2.43 (dd, 1H, J ) 13.4, 7.0 Hz), 1.70 (m, 2H), 1.49-1.31 (m,
4H), 1.45 (s, 9H), 1.38 (d, 3H, J ) 7.0 Hz), 1.12 (d, 3H, J ) 7.0
Hz), 0.94 (t, 3H, J ) 7.2 Hz); 13C NMR (MeOD, 100 MHz) δ
178.0, 173.6, 172.2, 156.4, 129.6, 121.4, 80.1, 69.6, 54.6, 53.2,
48.8, 39.1, 38.2, 37.7, 33.5, 32.7, 31.6, 29.2, 27.6, 27.2, 20.1, 17.8,
16.3, 13.2; MS (FAB) m/z 575 (M + H+), 557, 457, 402; HRMS
calcd for C26H46N4O6S2 (M + H+) 575.2937, found 575.2953; LC/
MS retention time [A] 5.75 min, [B] 7.61 min.
(3S,6S,9S,1′S,3′R)-4-(9-Acetylamino-6-methyl-5,8-dioxo-1,11-
dithia-4,7-diaza-cyclopentadec-3-yl)-N-butyl-4-hydroxy-2-meth-
yl-butyramide (29). Into a solution of 23 (12 mg, 0.02 mmol) in
CH2Cl2 (2 mL) was added TFA (0.33 mL); the mixture was stirred
at room temperature for 30 min and then concentrated in a vacuum.
The residue was dissolved in DMF (2 mL) and cooled to 0 °C,
Ac2O (0.03 mL, 0.2 mmol) and NaHCO3 (30 mg, 0.35 mmol) were
added consecutively, and the mixture was stirred at 0 °C to room
temperature for 3 h. Solvent was removed under reduced pressure,
the residue was treated with 10% citric acid and extracted with
AcOEt, and the combined organic layers were washed with
saturated NaHCO3 and brine, dried over Na2SO4, and concentrated.
Flash chromatography of the residue gave pure 29 (5.4 mg, 50%):
(3S,6S,9S,1′S,3′R)-[3-(3-Butylcarbamoyl-1-hydroxy-butyl)-6-
methyl-5,8-dioxo-1,11-dithia-4,7-diaza-cycloheptadec-9-yl]-car-
bamic Acid tert-Butyl Ester (25). Compound 25 (14 mg, 43%)
was prepared from 22 (38 mg, 0.054 mmol) and 1,6-dibromohexane
(0.014 mL, 0.1 mmol) according to the general procedure for the
1
preparation of 23: [R]D -26 (c 0.6, MeOH); H NMR (MeOD,
400 MHz) δ 4.46 (m, 1H), 4.34 (m, 1H), 3.94 (m, 1H), 3.71 (m,
1H), 3.18 (m, 2H), 2.87-2.72 (m, 3H), 2.65-2.49 (m, 6H), 1.70-
1.50 (m, 5H), 1.49-1.35 (m, 10H), 1.45 (s, 9H), 1.38 (d, 3H, J )
7.1 Hz), 1.12 (d, 3H, J ) 7.0 Hz), 0.94 (t, 3H, J ) 7.2 Hz); 13C
NMR (MeOD, 100 MHz) δ 177.0, 173.4, 171.8, 156.3, 79.8, 69.0,
54.3, 53.7, 49.4, 39.0, 38.0, 37.7, 34.5, 33.1, 31.9, 31.6, 30.8, 29.1,
28.9, 27.6, 27.1, 26.5, 20.1, 17.9, 17.8, 13.2; MS (FAB) m/z 605
(M + H+), 531, 307, 154; HRMS calcd for C28H52N4O6S2 (M +
H+) 605.3420, found 605.3421; LC/MS retention time [A] 23.03
min, [B] 31.21 min.
1
[R]D -17.5 (c 0.4, MeOH); H NMR (MeOD, 400 MHz) δ 4.56
(m, 1H), 4.50 (m, 1H), 3.94 (m, 1H), 3.62 (m, 1H), 3.16 (m, 2H),
2.95-2.76 (m, 4H), 2.62-2.50 (m, 6H), 2.01 (s, 3H), 1.67 (m,
4H), 1.42-1.35 (m, 6H), 1.37 (d, 3H, J ) 7.1 Hz), 1.11 (d, 3H, J
) 7.0 Hz), 0.94 (t, 3H, J ) 7.2 Hz); MS (ESI) m/z 519 (M + H+),
338, 258; HRMS calcd for C23H42N4O5S2 (M + H+) 519.2669,
found 519.2670; LC/MS retention time [A] 4.38 min, [B] 6.83 min.
(5S,8S,11S,1′S,3′R)-[5-(3-Butylcarbamoyl-1-hydroxy-butyl)-
8-methyl-7,10-dioxo-3,13-dithia-6,9-diaza-bicyclo[13.2.2]nonadeca-
1(18),15(19),16-trien-11-yl]-carbamic Acid tert-Butyl Ester (26).
Compound 26 (20 mg, 49%) was prepared from 22 (46 mg, 0.065
mmol) and 1,4-bis-bromomethyl-benzene (35 mg, 0.12 mmol)
according to the general procedure for the preparation of 23: [R]D
(3S,6S,9S,1′S,3′R)-4-(9-Acetylamino-6-methyl-5,8-dioxo-1,11-
dithia-4,7-diaza-cyclohexadec-3-yl)-N-butyl-4-hydroxy-2-methyl-
butyramide (30). Compound 30 (2 mg, 55%) was prepared from
24 (4 mg, 0.007 mmol) and acetic anhydride (0.01 mL, 0.07 mmol)
according to the general procedure for the preparation of 29: [R]D
1
-28.3 (c 0.3, MeOH); H NMR (MeOD, 400 MHz) δ 4.55 (m,
1
-25.9 (c 0.5, MeOH); H NMR (MeOD, 400 MHz) δ 7.37-7.24
1H), 4.48 (m, 1H), 3.97 (m, 1H), 3.65 (m, 1H), 3.18 (m, 2H), 2.93-
2.80 (m, 4H), 2.67-2.46 (m, 6H), 1.98 (s, 3H), 1.69-1.56 (m,
4H), 1.52-1.41 (m, 8H), 1.38 (d, 3H, J ) 7.0 Hz), 1.13 (d, 3H, J
) 6.9 Hz), 0.94 (t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz)
δ 179.8, 173.5, 171.8, 171.2, 69.4, 63.1, 53.2, 53.0, 49.3, 46.4,
38.1, 37.7, 33.8, 32.7, 31.9, 31.6, 30.6, 28.0, 26.7, 21.4, 20.1, 17.9,
17.8, 13.2; MS (ESI) m/z 533 (M + H+), 515, 460; HRMS calcd
for C24H44N4O5S2 (M + H+) 533.2831, found 533.2850; LC/MS
retention time [A] 16.90 min, [B] 7.19 min.
(m, 4H), 4.37 (m, 1H), 4.28 (m, 1H), 4.06 (m, 1H), 3.94-3.57 (m,
5H), 3.18 (m, 2H), 2.76 (m, 1H), 2.50 (m, 3H), 2.30 (m, 1H), 1.68
(m, 2H), 1.55-1.30 (m, 4H), 1.46 (s, 9H), 1.33 (d, 3H, J ) 6.8
Hz), 1.14 (d, 3H, J ) 7.0 Hz), 0.95 (t, 3H, J ) 7.4 Hz); 13C NMR
(MeOD, 100 MHz) δ 179.5, 173.8, 172.1, 156.5, 137.8, 131.6,
131.3, 130.7, 81.0, 68.5, 62.1, 54.4, 52.9, 40.5, 40.1, 39.1, 34.9,
34.8, 33.1, 31.1, 29.1, 21.6, 19.0, 14.6; MS (ESI) m/z 625 (M +
H+), 607, 507, 452; HRMS calcd for C30H48N4O6S2 (M + H+)
625.3094, found 625.3121; LC/MS retention time [A] 23.58 min,
[B] 8.47 min.
(3S,6S,9S,1′S,3′R)-[3-(3-Butylcarbamoyl-1-hydroxy-butyl)-6-
methyl-5,8-dioxo-1,11-dithia-4,7-diaza-cyclopentadec-13-en(cis)-
9-yl]-carbamic Acid tert-Butyl Ester (27). Compound 27 (15 mg,
40%) was prepared from 22 (46 mg, 0.065 mmol) and cis-1,4-
dibromo-2-butene (28 mg, 0.13 mmol) according to the general
procedure for the preparation of 23: [R]D -56.1 (c 0.34, MeOH);
1H NMR (MeOD, 400 MHz) δ 5.65 (m, 1H), 5.52 (m, 1H), 4.51
(m, 1H), 4.31 (m, 1H), 3.96 (m, 1H), 3.58 (m, 2H), 3.47 (m, 1H),
3.17 (m, 2H), 3.07 (m, 2H), 2.85 (m, 2H), 2.70 (m, 1H), 2.57 (m,
2H), 1.74 (m, 4H), 1.52-1.32 (m, 5H), 1.45 (s, 9H), 1.36 (d, 3H,
J ) 7.0 Hz), 1.11 (d, 3H, J ) 7.0 Hz), 0.94 (t, 3H, J ) 7.2 Hz);
13C NMR (MeOD, 100 MHz) δ 177.9, 173.5, 172.5, 156.6, 130.4,
126.9, 80.2, 70.4, 56.3, 54.1, 49.5, 39.1, 38.1, 37.7, 35.0, 31.6, 30.9,
29.2, 28.4, 27.6, 20.1, 17.9, 16.5, 13.2; MS (FAB) m/z 575 (M +
H+), 557, 457, 402; HRMS calcd for C26H46N4O6S2 (M + H+)
575.2937, found 575.2947; LC/MS retention time [A] 5.79 min,
[B] 7.60 min.
(3S,6S,9S,1′S,3′R)-4-(9-Acetylamino-6-methyl-5,8-dioxo-1,11-
dithia-4,7-diaza-cycloheptadec-3-yl)-N-butyl-4-hydroxy-2-meth-
yl-butyramide (31). Compound 31 (5 mg, 60%) was prepared from
25 (9 mg, 0.013 mmol) and acetic anhydride (0.016 mL, 0.13 mmol)
according to the general procedure for the preparation of 29: [R]D
1
-37.1 (c 0.35, MeOH); H NMR (MeOD, 400 MHz) δ 4.52 (m,
1H), 4.46 (m, 1H), 3.92 (m, 1H), 3.66 (m, 1H), 3.18 (m, 2H), 2.90-
2.74 (m, 3H), 2.65-2.50 (m, 6H), 1.98 (s, 3H), 1.63-1.50 (m,
5H), 1.49-1.35 (m, 8H), 1.38 (d, 3H, J ) 7.0 Hz), 1.12 (d, 3H, J
) 7.0 Hz), 0.94 (t, 3H, J ) 7.2 Hz); 13C NMR (MeOD, 100 MHz)
δ 177.9, 173.4, 171.9, 171.2, 69.1, 64.6, 53.7, 53.6, 49.4, 39.0,
37.7, 34.1, 31.9, 31.6, 29.1, 28.9, 27.0, 26.5, 21.4, 20.1, 17.9, 17.8,
13.2; MS (ESI) m/z 547 (M + H+), 529, 474; HRMS calcd for
C25H46N4O5S2 (M + H+) 547.2987, found 547.2975; LC/MS
retention time [A] 18.59 min, [B] 27.39 min.
(2R,4S,5′S,8′S,11′S)-4-(11-Acetylamino-8-methyl-7,10-dioxo-
3,13-dithia-6,9-diaza-bicyclo[13.2.2]nonadeca-1(18),15(19),16-
trien-5-yl)-N-butyl-4-hydroxy-2-methyl-butyramide (32). Com-
pound 32 (4 mg, 45%) was prepared from 26 (10 mg, 0.016 mmol)
and acetic anhydride (0.015 mL, 0.16 mmol) according to the
(3S,6S,9S,1′S,3′R)-[3-(3-Butylcarbamoyl-1-hydroxy-butyl)-6-
methyl-5,8-dioxo-1,11-dithia-4,7-diaza-cyclopentadec-13-en(trans)-

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4557
general procedure for the preparation of 29: [R]D -41 (c 0.3,
MeOH); 1H NMR (MeOD, 400 MHz) δ 7.38-7.30 (m, 4H), 4.34-
(m, 2H), 3.86 (m, 2H), 3.70 (m, 4H), 3.18 (m, 3H), 2.54 (m, 3H),
2.32 (m, 2H), 1.99 (s, 3H), 1.68 (m, 2H), 1.53-1.35 (m, 4H), 1.32
(d, 3H, J ) 7.0 Hz), 1.14 (d, 3H, J ) 7.0 Hz), 0.95 (t, 3H, J ) 7.3
Hz); MS (ESI) m/z 567 (M + H+); HRMS calcd for C27H42N4O5S2
(M + H+) 567.2669, found 567.2669; LC/MS retention time [A]
5.26 min, [B] 7.60 min.
at room temperature for 24 h, and then MeOH (2 mL) was added.
After being stirred for 2 h, the solution was concentrated, and the
residue was treated with 10% citric acid (2 mL) and extracted with
AcOEt (3 × 20 mL). The combined organic layers were washed
with brine, dried over MgSO4, and concentrated. Flash chroma-
tography (hexane/AcOEt 2/1) of the residue gave 36 (0.1 g, 91%),
and 19 (30 mg) was also recovered: [R]D +28.1 (c 1.4, CHCl3);
1H NMR (CHCl3, 400 MHz) δ 7.34-7.23 (m, 5H), 4.80 (d, 1H, J
) 7.6 Hz), 4.08 (m, 1H), 3.73 (s, 2H), 3.71 (m, 1H), 2.52 (m, 3H),
1.96 (m, 1H), 1.49 (s, 9H), 1.24 (d, 3H, J ) 7.0 Hz), 0.88 (s, 9H),
0.05 (s, 3H), -0.06 (s, 3H); 13C NMR (CHCl3, 100 MHz) δ 180.8,
156.5, 138.5, 129.5, 128.9, 127.5, 80.3, 69.9, 51.9, 38.0, 36.6, 36.1,
33.8, 28.8, 26.3, 18.4, 16.9, -3.9, -4.2; MS (FAB) m/z 498 (M +
H+), 398, 154; HRMS calcd for C30H52NO6SSi (M + H+) 498.2709,
found 498.2708.
(2R,4S,5S,2′S)-6-Benzylsulfanyl-5-[2-(3-benzylsulfanyl-propio-
nylamino)-propionylamino]-4-hydroxy-2-methyl-hexanoic Acid
Butylamide (33). Into a solution of 21 (0.15 g, 0.29 mmol) in CH2-
Cl2 (4.5 mL) was added TFA (0.75 mL). The mixture was stirred
at room temperature for 30 min and concentrated, and the residue
was dissolved in CH2Cl2 (8 mL), cooled to 0 °C, then treated with
3-benzylsulfanyl propionic acid (0.11 g, 0.58 mmol), PyBOP (0.23
g, 0.44 mmol), and DIEA (0.28 mL, 1.45 mmol) successively. The
mixture was stirred at 0 °C to room temperature for 3 h and
concentrated, the residue was treated with 10% citric acid (2 mL)
and extracted with AcOEt (3 × 30 mL), and the combined organic
layers were washed with saturated NaHCO3 and brine, dried over
Na2SO4, and concentrated. Flash chromatography (4% MeOH in
AcOEt) of the residue gave pure 33 (120 mg, 70%): 1H NMR
(MeOD, 400 MHz) δ 7.41-7.22 (m, 10H), 4.36 (m, 1H), 3.92 (m,
1H), 3.74 (m, 5H), 3.21 (m, 4H), 2.66 (m, 3H), 2.51 (m, 4H), 1.64
(m, 1H), 1.47 (m, 2H), 1.42-1.31 (m, 2H), 1.36 (d, 3H, J ) 7.0
Hz), 1.10 (d, 3H, J ) 7.1 Hz), 0.92 (t, 3H, J ) 7.3 Hz); 13C NMR
(MeOD, 100 MHz) δ 177.9, 174.1, 173.3, 138.9, 129.2, 129.0,
128.5, 128.4, 126.9, 126.1, 125.5, 68.7, 64.2, 54.8, 52.8, 49.8, 46.9,
39.1, 38.3, 37.7, 35.9, 35.7, 31.6, 26.9, 20.1, 17.7, 17.3, 13.2; MS
(FAB) m/z 588 (M + H+), 570, 460, 307; HRMS calcd for
C31H45N3O4S2 (M + H+) 588.2929, found 588.2922.
(3S,6S,1′S,3′R)-N-Butyl-4-hydroxy-2-methyl-4-(6-methyl-5,8-
dioxo-1,11-dithia-4,7-diaza-cyclopentadec-13-en-3-yl)-butyramide
(34). Compound 34 (11 mg, 51%) was prepared from 33 (28 mg,
0.047 mmol) and cis-1,4-dibromo-2-butene (0.025 mL, 0.15 mmol)
according to the general procedure for the preparation of 23: [R]D
-30 (c 0.1, MeOH); 1H NMR (MeOD, 400 MHz) δ 7.78 (b, 1H),
7.60 (d, 1H, J ) 9.1), 5.69 (m, 1H), 5.51 (m, 1H), 4.47 (dd, 1H, J
) 14.5, 7.2 Hz), 3.96 (m, 1H), 3.54 (m, 3H), 3.16 (dd, 1H, J )
12.6, 7.0 Hz), 3.02 (m, 2H), 2.86 (m, 2H), 2.72-2.54 (m, 4H),
1.72 (m, 1H), 1.53-1.29 (m, 4H), 1.43 (d, 3H, J ) 7.1 Hz), 1.12
(d, 3H, J ) 7.0 Hz), 0.94 (t, 3H, J ) 7.3 Hz); 13C NMR (DMSO,
100 MHz) δ 176.1, 172.8, 172.1, 130.0, 128.5, 70.2, 56.5, 49.0,
39.0, 38.2, 37.7, 36.7, 32.2, 32.0, 29.6, 29.3, 27.8, 20.4, 19.7, 18.1,
14.6; MS (FAB) m/z 460 (M + H+), 307, 154; HRMS calcd for
C21H37N3O4S2 (M + H+) 460.2304, found 460.2301; LC/MS
retention time [A] 16.14 min, [B] 6.83 min.
(3S,6S,1′S,3′R)-N-Butyl-4-hydroxy-2-methyl-4-(6-methyl-5,8-
dioxo-1,11-dithia-4,7-diaza-cyclopentadec-13-en-3-yl)-butyramide
(35). Compound 35 (8 mg, 45%) was prepared from 33 (23 mg,
0.039 mmol) and trans-1,4-dibromo-2-butene (30 mg, 0.14 mmol)
according to the general procedure for the preparation of 23: [R]D
-24 (c 0.1, MeOH); 1H NMR (MeOD, 400 MHz) δ 5.56 (m, 2H),
4.44 (dd, 1H, J ) 14.2, 7.1 Hz), 3.74 (m, 1H), 3.68 (m, 1H), 3.22-
3.02 (m, 6H), 2.84 (m, 3H), 2.60 (m, 2H), 2.46 (m, 2H), 1.72 (m,
1H), 1.53-1.39 (m, 4H), 1.37 (d, 3H, J ) 7.1 Hz), 1.12 (d, 3H, J
) 7.0 Hz), 0.94 (t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz)
δ 177.9, 173.6, 173.5, 130.4, 128.7, 69.2, 54.3, 49.3, 39.0, 38.4,
37.8, 35.5, 32.9, 32.8, 31.6, 31.1, 28.0, 20.1, 17.9, 16.0, 13.2; MS
(FAB) m/z 460 (M + H+), 338, 307, 154; HRMS calcd for
C21H37N3O4S2 (M + H+) 460.2304, found 460.2307; LC/MS
retention time [A] 15.96 min, [B] 6.95 min.
(2R,4S,5S)-6-Benzylsulfanyl-5-tert-butoxycarbonylamino-4-
(tert-butyl-dimethyl-silanyloxy)-2-methyl-hexanoic Acid (36).
Into a solution of 19 (0.11 g, 0.3 mmol) in 1,2-dimethoxyethane
(1.8 mL) was added 1 N LiOH (1.8 mL). The mixture was stirred
at room temperature for 3 h and then partitioned between 10% citric
acid (2 mL) and AcOEt (20 mL). The organic layers were washed
with brine, dried over MgSO4, and concentrated. The residue was
dissolved in DMF (2 mL), and then TBSCl (0.27 g, 1.8 mmol) and
imidazole (0.25 g, 3.6 mmol) were added. The mixture was stirred
(1S,2S,4R,1′S)-[1-Benzylsulfanylmethyl-4-(1-butylcarbamoyl-
2-methyl-propylcarbamoyl)-2-(tert-butyldimethylsilanyloxy)-
pentyl]-carbamic Acid tert-Butyl Ester (37). Into a solution of
36 (0.22 g, 0.44 mmol) and Val N-n-Bu (0.12 g, 0.52 mmol) in
CH2Cl2 (6 mL) was added PyBOP (0.28 g, 0.53 mmol) at 0 °C,
followed by DIEA (0.38 mL, 2.2 mmol). The mixture was stirred
at 0 °C to room temperature for 3 h, then 10% citric acid (2 mL)
was added, and the mixture was extracted with AcOEt (3 × 30
mL). The combined organic layers were washed with brine, dried
over MgSO4, and concentrated. Flash chromatography (hexane/
AcOEt 3/1) of the residue gave 37 (0.2 g, 86%): [R]D +4.7 (c 0.9,
1
CHCl3); H NMR (CHCl3, 400 MHz) δ 7.34-7.23 (m, 5H), 6.74
(m, 1H), 6.45 (d, 1H, J ) 8.9 Hz), 4.72 (d, 1H, J ) 9.6 Hz), 4.2
(m, 1H), 3.96 (m, 1H), 3.73 (s, 2H), 3.28 (m, 1H), 3.14 (m, 1H),
2.45 (d, 2H, J ) 7.2 Hz), 2.28 (m, 1H), 2.02 (m, 1H), 1.81 (m,
1H), 1.76 (m, 2H), 1.45 (s, 9H), 1.32 (m, 2H), 1.08 (d, 3H, J )
6.7 Hz), 0.95 (m, 9H), 0.88 (s, 9H), 0.02 (s, 3H), -0.01 (s, 3H);
13C NMR (CHCl3, 100 MHz) δ 176.5, 171.6, 156.4, 138.6, 129.5,
128.9, 127.5, 80.0, 69.7, 59.1, 51.4, 39.5, 38.7, 37.6, 36.5, 34.1,
32.0, 31.2, 28.8, 28.7, 26.2, 20.5, 19.7, 19.0, 18.4, 16.7, 14.1, -3.7,
-4.3; MS (FAB) m/z 652 (M + H+), 552; HRMS calcd for
C34H61N3O5SSi (M + H+) 652.4188, found 652.4188.
(1S,2S,4R,1′S)-[1-Benzylsulfanylmethyl-4-(1-butylcarbamoyl-
2-methyl-propylcarbamoyl)-2-hydroxy-pentyl]-carbamic Acid
tert-Butyl Ester (38). In procedure 1, into a solution of 37 (0.2 g,
0.3 mmol) in MeOH (12 mL) was added p-toluenesulfonic acid
(91 mg, 0.33 mmol). The mixture was stirred at room temperature
for 3 h, then saturated aqueous NaHCO3 (2 mL) was added, and
the mixture was extracted with AcOEt (3 × 30 mL). The combined
organic layers were washed with brine, dried over MgSO4, and
concentrated. Flash chromatography (hexane/AcOEt 3/1) of the
residue gave 38 (80 mg, 50%). In procedure 2, into a solution of
19 (56 mg, 0.15 mmol) in toluene (1.2 mL) was added Val N-n-
Bu (87 mg, 0.3 mmol) and 2-hydroxypyridine (16 mg, 0.17 mmol).
The mixture was heated to reflux for 3 days. After cooling, the
solvent was evaporated; the residue was purified by flash chroma-
tography (hexane/AcOEt 3/1, 1/2) to give 38 (53 mg, 66%): [R]D
1
-28.2 (c 0.9, MeOD); H NMR (MeOD, 400 MHz) δ 7.34-7.23
(m, 5H), 6.14 (d, 1H, J ) 9.5 Hz), 4.12 (d, 1H, J ) 7.8 Hz), 3.74
(s, 2H), 3.63 (m, 2H), 3.16 (m, 2H), 2.65 (m, 1H), 2.59 (dd, 1H, J
) 13.9, 7.0 Hz), 2.45 (dd, 2H, J ) 13.7, 7.5 Hz), 2.01 (m, 1H),
1.75 (m, 1H), 1.49 (m, 2H), 1.46 (s, 9H), 1.35 (m, 2H), 1.12 (d,
3H, J ) 6.9 Hz), 0.94 (m, 9H); 13C NMR (MeOD, 100 MHz) δ
177.9, 172.6, 157.4, 138.8, 129.2, 128.4, 126.9, 79.2, 69.2, 59.4,
54.2, 39.0, 38.3, 37.5, 35.5, 32.9, 31.5, 31.0, 27.8, 20.1, 18.9, 18.2,
17.7, 13.1; MS (FAB) m/z 538 (M + H+), 438, 307, 154; HRMS
calcd for C28H47N3O5S (M + H+) 538.3301, found 538.3307.
(1S,2S,4R,1′S,1′′S)-{1-[1-Benzylsulfanylmethyl-4-(1-butylcar-
bamoyl-2-methyl-propylcarbamoyl)-2-hydroxy-pentylcarbam-
oyl]-ethyl}-carbamic Acid tert-Butyl Ester (39). Into a solution
of 38 (70 mg, 0.13 mmol) in CH2Cl2 (3 mL) was added TFA (0.5
mL). The mixture was stirred at room temperature for 30 min and
then concentrated under vacuum. The residue was dissolved in CH2-
Cl2 (3 mL) and cooled to 0 °C, and N-Boc alanine (0.05 g, 0.26
mmol), PyBOP (0.1 g, 0.2 mmol), and DIEA (0.11 mL, 0.65 mmol)
were added consecutively. The mixture was stirred at 0 °C to room

4558 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
temperature for 3 h and then concentrated. The residue was treated
with 10% citric acid (2 mL) and extracted with AcOEt (3 × 20
mL). The combined organic layers were washed with saturated
NaHCO3 and brine, dried over Na2SO4, and concentrated. Flash
chromatography (AcOEt/hexane 2/1) of the residue gave pure 39
(65 mg, 82%): [R]D -49.2 (c 0.9, MeOD); 1H NMR (MeOD, 400
MHz) δ 8.01 (b, 1H), 7.69 (d, 1H, J ) 8.2 Hz), 7.47 (d, 1H, J )
9.2 Hz), 7.34-7.19 (m, 5H), 4.10 (m, 2H), 3.93 (m, 1H), 3.80 (m,
1H), 3.73 (s, 2H), 3.26-3.13 (m, 2H), 2.64 (m, 1H), 2.61 (dd, 1H,
J ) 13.7, 7.4 Hz), 2.50 (dd, 2H, J ) 13.8, 7.2 Hz), 2.03 (m, 1H),
1.67 (m, 1H), 1.49 (m, 4H), 1.44 (s, 9H), 1.38-1.29 (m, 6H), 1.11
(d, 3H, J ) 6.9 Hz), 0.94 (m, 9H); 13C NMR (MeOD, 100 MHz)
δ 177.9, 175.1, 172.7, 156.4, 138.7, 129.2, 128.5, 126.9, 79.6, 68.5,
59.6, 52.6, 51.1, 39.2, 38.6, 37.5, 35.5, 32.7, 31.5, 31.0, 27.8, 20.1,
18.9, 18.2, 17.5, 16.9, 13.1; MS (FAB) m/z 609 (M + H+), 536,
436, 307, 154; HRMS calcd for C31H52N4O6S (M + H+) 609.3686,
found 609.3682.
5,6-Dihydro-4H-pyridine-1,2-dicarboxylic Acid 1-tert-Butyl
Ester 2-(2-Trimethylsilanyl-ethyl) Ester (45). Into a solution of
44 (1.23 g, 5.4 mmol) in THF (27 mL) was added PPh3 (3.4 g,
13.4 mmol) and trimethylsilyl ethanol (1.2 mL, 8.1 mmol). The
mixture was cooled to 0 °C, and diethylazodicarboxylate (DEAD)
(1.9 mL, 12.0 mmol) was added dropwise. The mixture was stirred
at 0 °C to room temperature for 2 h until the reaction was complete.
The solution was partitioned between Et2O (100 mL) and saturated
NaHCO3 (60 mL) and extracted with Et2O twice, and the combined
organic layers were dried over Na2SO4 and concentrated. Flash
chromatography (hexane/AcOEt 8/1) of the residue gave 45 (1.26
g, 72%): 1H NMR (CDCl3, 400 MHz) δ 5.98 (t, 1H, J ) 3.8 Hz),
4.26 (t, 2H, J ) 8.64 Hz), 3.59 (t, 2H, J ) 5.5 Hz), 2.22 (m, 2H),
1.81 (m, 2H), 1.45 (s, 9H), 1.05 (t, 2H, J ) 8.6 Hz), 0.06 (s, 9H);
13C NMR (CDCl3, 100 MHz) δ 165.8, 153.5, 133.7, 121.9, 81.7,
63.6, 43.5, 28.5, 23.4, 23.1, 17.7, -1.1; MS (ESI) m/z 328 (M +
H+); HRMS calcd for C16H29NO4Si (M + H+) 328.1939, found
328.1928.
(1S,1′S,1′′S,2′′S,4′′R,1′′′S)-(2-Benzylsulfanyl-1-{1-[1-benzylsul-
fanylmethyl-4-(1-butylcarbamoyl-2-methyl-propylcarbamoyl)-
2-hydroxy-pentylcarbamoyl]-ethylcarbamoyl}-ethyl)-carbam-
ic Acid tert-Butyl Ester (40). Into a solution of 39 (0.065 g, 0.11
mmol) in CH2Cl2 (3 mL) was added TFA (0.5 mL). The mixture
was stirred at room temperature for 30 min and then concentrated
under vacuum. The residue was dissolved in CH2Cl2 (3 mL) and
cooled to 0 °C. N-Boc S-benzyl cysteine (0.067 g, 0.22 mmol),
PyBOP (0.083 g, 0.17 mmol), and DIEA (0.093 mL, 0.55 mmol)
were added consecutively. The mixture was stirred at 0 °C to room
temperature for 3 h and then concentrated. Processing as described
for 39 gave a residue, which was purified by flash chromatography
(AcOEt) to give pure 40 (52 mg, 61%): [R]D -53.8 (c 0.9, MeOD);
1H NMR (MeOD, 400 MHz) δ 8.05 (b, 1H), 7.71 (d, 1H, J ) 8.2
Hz), 7.56 (d, 1H, J ) 9.0 Hz), 7.34-7.19 (m, 10H), 4.41 (m, 1H),
4.29 (m, 1H), 4.12 (m, 1H), 3.97 (m, 1H), 3.77 (s, 4H), 3.69 (m,
2H), 3.25-3.13 (m, 2H), 2.86-2.69 (m, 4H), 2.58 (m, 2H), 2.03
(m, 1H), 1.69 (m, 1H), 1.46 (s, 9H), 1.40 (d, 3H, J ) 7.0 Hz),
1.48-1.34 (m, 6H), 1.10 (d, 3H, J ) 6.9 Hz), 0.94 (m, 9H); 13C
NMR (MeOD, 100 MHz) δ 177.9, 173.6, 172.7, 172.2, 156.7,
138.7, 138.5, 129.2, 128.5, 128.4, 127.1, 127.0, 126.9, 79.9, 76.6,
68.9, 59.5, 53.9, 52.6, 39.2, 38.5, 36.1, 36.0, 35.6, 33.3, 32.5, 31.5,
31.0, 27.7, 20.1, 18.9, 18.2, 17.3, 13.1; MS (FAB) m/z 801 (M +
H+), 729, 530, 266, 173; HRMS calcd for C41H63N5O7S2 (M +
H+) 802.4247, found 802.4245.
3-Benzylsulfanyl-piperidine-1,2-dicarboxylic Acid 1-tert-Butyl
Ester 2-(2-Trimethylsilanyl-ethyl) Ester (46). Into a solution of
45 (1.0 g, 3.05 mmol) in MeOH (22 mL) was added benzyl
mercaptan (1.36 mL, 10.7 mmol); then a freshly prepared solution
of NaOMe in MeOH (0.5 M, 18 mL) was added dropwise at room
temperature. The mixture was stirred at room temperature for 7 h
until the reaction was complete; then Amberlite IR 120(+) was
added to pH 7, the resin was filtered and washed with MeOH, and
the filtrate was concentrated. Flash chromatography (hexane/AcOEt
8/1) of the residue gave 46 (1.08 g, 78%): 1H NMR (CDCl3, 400
MHz, 55 °C) δ 7.36-7.23 (m, 5H), 4.94 (b, 1H), 4.26-4.18 (m,
2H), 4.04, 3.94 (b, 1H), 3.84 (m, 2H), 3.16, 2.95 (b, 1H), 1.92-
1.82 (m, 1H), 1.77-1.64 (m, 2H), 1.51-1.30 (m, 2H), 1.48, 1.46
(s, 9H), 1.08-0.96 (m, 2H), 0.06, 0.05 (s, 9H); 13C NMR (CDCl3,
100 MHz, 55 °C) δ 170.3, 156.4, 137.9, 137.8, 128.7, 128.6, 128.3,
126.9, 80.1, 79.9, 63.4, 62.8, 41.8, 36.1, 35.7, 28.2, 28.1, 26.4, 26.2,
19.8, 17.5, 17.4, -1.7; MS (ESI) m/z 474 (M + Na+), 352 (M-
Boc)+. HRMS calcd for C23H37NO4SSi (M + H+) 452.2285, found
452.2295.
cis-3-Benzylsulfanyl-piperidine-2-carboxylic Acid 2-Trimethyl-
silanyl-ethyl Ester (47). Into a solution of 46 (0.36 g, 0.8 mmol)
in CH2Cl2 (18 mL) was added TFA (3 mL). The mixture was stirred
at room temperature for 40 min. The solvent and excess TFA were
removed under reduced pressure. The residue was treated with
AcOEt (20 mL), washed with saturated NaHCO3 and brine, dried
over Na2SO4, and concentrated. Flash chromatography (hexane/
AcOEt 2/1) of the residue gave the desired cis product 47 (0.11 g,
39%) and the trans isomer (0.10 g, 36%), which was discarded:
1H NMR (CDCl3, 400 MHz) δ 7.35-7.24 (m, 5H), 4.26 (dd, 1H,
J ) 11.1, 6.8 Hz), 4.16 (dd, 1H, J ) 11.0, 6.6 Hz), 3.72 (ab, 2H,
J ) 13.3 Hz), 3.61 (d, 1H, J ) 2.8 Hz), 3.14 (m, 1H), 2.59 (m,
1H), 1.85 (m, 5H), 1.44 (m, 1H), 1.0 (m, 2H), 0.07 (s, 9H); 13C
NMR (CDCl3, 100 MHz) δ 171.6, 139.2, 129.3, 128.6, 127.3, 63.6,
63.3, 46.1, 44.8, 37.1, 31.4, 22.1, 17.8, -1.1; MS (ESI) m/z 352
(M + H+).
cis-3-Benzylsulfanyl-piperidine-1,2-dicarboxylic Acid 1-tert-
Butyl Ester 2-(2-Trimethylsilanyl-ethyl) Ester (48). Into a
solution of 47 (80 mg, 0.21 mmol) in MeOH (4 mL) was added
NaHCO3 (46 mg, 0.53 mmol) and (Boc)2O (60 mg, 0.23 mmol).
The mixture was stirred in an ultrasonic bath for 3 h. After cooling,
the excess NaHCO3 was filtered off, and the filtrate was evaporated.
The residue was treated with Et2O (30 mL) and filtered again, the
filtrate was concentrated, and the residue was purified by flash
chromatography (hexane/AcOEt 8/1) to give 48 (90 mg, 90%): 1H
NMR (CDCl3, 400 MHz) δ 7.35-7.26 (m, 5H), 5.09, 4.84 (b, 1H),
4.24 (m, 2H), 3.94-3.78 (m, 31H), 3.26 (m, 2H), 2.68 (m, 1H),
1.89 (m, 1H), 1.73 (m, 2H), 1.46 (s, 9H), 1.37 (m, 1H), 1.06 (m,
2H), 0.05 (s, 9H); 13C NMR (CDCl3, 100 MHz) δ 170.6, 156.4,
138.2, 129.1, 128.9, 127.0, 80.1, 63.4, 57.6, 41.7, 40.5, 36.1, 28.2,
27.0, 26.5, 19.8, -1.7; MS (ESI) m/z 452 (M + H+); HRMS calcd
for C23H37NO4SSi (M + H+) 452.2285, found 452.2295.
cis-3-Benzylsulfanyl-piperidine-1,2-dicarboxylic acid 1-tert-
butyl ester (49). Into a suspension of 48 (105 mg, 0.23 mmol)
(3S,6S,9S,1′S,3′R,1′′S)-{3-[3-(1-Butylcarbamoyl-2-methyl-pro-
pylcarbamoyl)-1-hydroxy-butyl]-6-methyl-5,8-dioxo-1,11-dithia-
4,7-diaza-cyclopentadec-13-en-9-yl}-carbamic Acid tert-Butyl
Ester (41). Compound 41 (5.5 mg, 24%) was prepared from 40
(28 mg, 0.035 mmol) and cis-1,4-dibromo-2-butene (15 mg, 0.07
mmol) according to the general procedure for the preparation of
23: [R]D -22 (c 0.1, MeOD); 1H NMR (MeOD, 400 MHz) δ 5.65
(m, 1H), 5.52 (m, 1H), 4.54 (d, 1H, J ) 7.1 Hz), 4.31 (m, 1H),
3.98 (m, 1H), 3.60 (m, 1H), 3.48 (m, 1H), 3.24-3.05 (m, 6H),
2.92-2.79 (m, 2H), 2.68 (m, 2H), 2.54 (m, 2H), 1.76 (m, 1H),
1.60-1.38 (m, 5H), 1.45 (s, 9H), 1.40 (d, 3H, J ) 7.0 Hz), 1.12
(d, 3H, J ) 6.9 Hz), 0.94 (m, 9H); MS (ESI) m/z 674 (M + H+);
HRMS calcd for C31H55N5O7S2 (M + H+) 674.3616, found
674.3612; LC/MS retention time [A] 6.06 min, [B] 7.89 min.
(3S,6S,9S,1′S,3′R,1′′S)-{3-[3-(1-Butylcarbamoyl-2-methyl-pro-
pylcarbamoyl)-1-hydroxy-butyl]-6-methyl-5,8-dioxo-1,11-dithia-
4,7-diaza-cyclopentadec-13-en-9-yl}-carbamic Acid tert-Butyl
Ester (42). Compound 42 (3 mg, 22%) was prepared from 40 (17
mg, 0.02 mmol) and trans-1,4-dibromo-2-butene (14 mg, 0.06
mmol) according to the general procedure for the preparation of
1
23: [R]D -35.2 (c 0.11, MeOD); H NMR (MeOD, 400 MHz) δ
8.04 (bs, 1H), 7.74 (d, 1H, J ) 8.7 Hz), 5.59 (m, 2H), 4.51 (m,
1H), 4.34 (m, 1H), 4.10 (m, 1H), 3.85 (m, 1H), 3.70 (m, 1H), 3.24-
3.03 (m, 4H), 2.95-2.82 (m, 4H), 2.69 (m, 1H), 2.04 (m, 1H),
1.73 (m, 1H), 1.61-1.28 (m, 6H), 1.46 (s, 9H), 1.38 (d, 3H, J )
7.2 Hz), 1.12 (d, 3H, J ) 7.1 Hz), 0.94 (m, 9H); 13C NMR (MeOD,
100 MHz); MS (FAB) m/z 675 (M + H+), 613, 460, 307; HRMS
calcd for C31H55N5O7S2 (M + H+) 674.3616, found 674.3616; LC/
MS retention time [A] 5.97 min, [B] 7.97 min.

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4559
and molecular sieves 4 Å in THF (1.9 mL) was added tetrabutyl
ammonium fluoride (TBAF; 1 N in THF, 0.5 mL) at 0 °C. The
mixture was stirred at 0 °C to room temperature for 5 h; then 10%
citric acid was added to pH 3.0, and the mixture was extracted
with AcOEt (3 × 20 mL). The combined organic layers were
sequentially washed with 10% citric acid, then with brine, dried
over Na2SO4, and concentrated to give the acid 49 (80 mg, quant):
1H NMR (CDCl3, 400 MHz) δ 9.2 (b, 1H), 7.36-7.26 (m, 5H),
5.15, 4.87 (b, 1H), 3.96 (b, 1H), 3.86 (m, 2H), 3.28 (m, 1H), 2.68
(b, 1H), 1.74 (m, 4H), 1.47 (s, 9H); 13C NMR (CDCl3, 100 MHz)
δ 174.6, 156.5, 138.1, 129.3, 128.9, 127.6, 81.1, 59.2, 41.6, 36.3,
28.7, 27.0, 25.5, 24.4, 20.3; MS (ESI) m/z 352 (M + H+).
3-Benzylsulfanyl-2-[1-(1-benzylsulfanylmethyl-4-butylcar-
bamoyl-2-hydroxy-pentylcarbamoyl)-ethylcarbamoyl]-piperidine-
1-carboxylic Acid tert-Butyl Ester (50). Into a solution of 49 (90
mg, 0.26 mmol) and 5-(2-amino-propionylamino)-6-benzylsulfanyl-
4-hydroxy-2-methyl-hexanoic acid butylamide (prepared separately,
0.13 g, 0.26 mmol) in CH2Cl2 (8 mL) was added PyBOP (0.2 g,
0.38 mmol) and DIEA (96 µL, 0.52 mmol) at 0 °C. The mixture
was stirred at 0 °C to room temperature for 4 h, and then 10%
citric acid (2 mL) was added. The mixture was extracted with
AcOEt (3 × 30 mL). The combined organic layers were sequentially
washed with saturated NaHCO3, then with brine, dried over Na2-
SO4, and concentrated to give a mixture of two diastereoisomers
50 (120 mg, 62%), which were inseparable; 1H NMR (MeOD, 400
MHz) δ 7.76 (b, 1H), 7.37-7.20 (m, 10H), 4.40 (b, 1H), 3.98 (m,
1H), 3.83 (m, 3H), 3.71 (m, 3H), 3.18 (m, 3H), 2.73 (m, 1H), 2.73
(m, 1H), 2.61 (m, 1H), 2.52 (m, 2H), 1.68 (m, 4H), 1.49 (m, 3H),
1.46 (s, 9H), 1.38 (m, 6H), 1.12 (d, 3H, J ) 6.9 HZ), 0.93 (t, 3H,
J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz) δ 177.9, 173.7, 172.1,
155.3, 138.8, 129.1, 129.0, 128.7, 128.5, 127.4, 127.3, 126.9, 126.4,
81.2, 68.9, 68.8, 64.5, 60.6, 53.3, 53.2, 52.9, 49.6, 42.9, 39.1, 38.2,
37.8, 37.7, 35.8, 32.7, 31.7, 31.7, 27.7, 20.1, 19.9, 17.7, 13.5, 13.2;
MS (ESI) m/z 765 (M + Na+), 643 (M-Boc)+. HRMS calcd for
C39H58N4O6S2 (M + H+) 743.3871, found 743.3870.
1.56 (m, 2H), 1.49 (s, 9H), 1.44 (d, 3H, J ) 7.1 HZ), 1.38 (m,
4H), 1.14 (d, 3H, J ) 7.0 Hz), 0.95 (t, 3H, J ) 7.3 Hz); 13C NMR
(MeOD, 100 MHz) δ 177.9, 173.4, 171.1, 155.7, 129.6, 129.2, 81.0,
54.2, 49.7, 48.8, 43.5, 40.6, 39.1, 38.0, 37.5, 33.7, 32.8, 32.4, 31.6,
28.9, 27.7, 26.1, 20.1, 18.0, 16.8, 13.2; MS (ESI) m/z 637 (M +
Na+); HRMS calcd for C29H50N4O6S2 (M + H+) 615.3245, found
615.3256; LC/MS retention time [A] 23.77 min, [B] 31.36 min.
(2S,4R,11′S,15′R,17′R,17a′R)-N-Butyl-4-hydroxy-2-methyl-4-
(15-methyl-14,17-dioxo-2,3,4,4a,6,9,11,12,13,14,15,16,17,17a-tet-
radecahydro-1H-5,10-dithia-1,13,16-triaza-benzocyclopentadecen-
12-yl)-butyramide (52). Into a solution of 51 (6 mg, 0.01 mmol)
in CH2Cl2 (3 mL) was added TFA (0.5 mL) dropwise. The mixture
was stirred at room temperature for 40 min and then evaporated.
The residue was dissolved in AcOEt (10 mL), washed sequentially
with saturated NaHCO3 (1 mL) and then with brine, dried over
NaSO4, and concentrated to give 52 (5 mg, quant): [R]D +21 (c
1
0.3, MeOH); H NMR (MeOD, 400 MHz) δ 5.63 (ddd, 1H, J )
14.5, 8.9, 5.4 Hz), 5.47 (m, 1H), 4.36 (q, 1H, J ) 7.1 Hz), 3.78
(dt, 1H, J ) 9.7, 3.1 Hz), 3.62 (m, 2H), 3.49 (m, 1H), 3.27 (m,
2H), 3.20 (m, 2H), 3.01 (dd, 1H, J ) 14.2, 7.9 Hz), 2.71 (m, 1H),
2.61 (m, 1H), 2.41 (dd, 1H, J ) 14.1, 3.4 Hz), 2.11 (m, 1H), 1.94
(m, 2H), 1.71 (ddd, 1H, J ) 13.6, 9.8, 3.4 Hz), 1.52 (m, 3H), 1.41
(d, 3H, J ) 7.1 Hz), 1.32 (m, 3H), 1.14 (d, 3H, J ) 7.0 Hz), 0.96
(t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz) δ 177.9, 174.0,
172.4, 131.5, 126.8, 68.0, 64.0, 55.8, 49.9, 48.8, 46.1, 45.3, 39.1,
39.0, 37.8, 33.4, 31.7, 30.9, 30.6, 20.9, 20.1, 17.9, 16.5, 13.1; MS
(ESI) m/z 515 (M + H+); HRMS calcd for C24H42N4O4S2 (M +
H+) 515.2720, found 515.2723; LC/MS retention time [A] 11.33
min, [B] 22.16 min.
(2S,4R,11′S,15′R,17′S,17a′S,)-N-Butyl-4-hydroxy-2-methyl-4-
(15-methyl-14,17-dioxo-2,3,4,4a,6,9,11,12,13,14,15,16,17,17a-tet-
radecahydro-1H-5,10-dithia-1,13,16-triaza-benzocyclopentadecen-
12-yl)-butyramide (54). Compound 54 (5.6 mg, quant) was
prepared from 53 (7 mg, 0.011 mmol) according to the procedure
1
for the preparation of 52: [R]D -102 (c 0.25, MeOH); H NMR
(MeOD, 400 MHz) δ 5.73 (m, 1H), 5.36 (m, 1H), 4.55 (q, 1H, J
) 7.0 Hz), 3.86 (m, 1H), 3.77 (m, 1H), 3.19 (m, 4H), 2.97 (td, 1H,
J ) 13.0, 4.0 Hz), 2.70 (m, 2H), 2.60 (m, 1H), 2.50 (dd, 1H, J )
14.3, 3.6 Hz), 2.04 (m, 2H), 1.94 (m, 1H), 1.70 (ddd, 1H, J )
13.5, 9.2, 3.8 Hz), 1.50 (m, 4H), 1.37 (d, 3H, J ) 7.0 Hz), 1.15 (d,
3H, J ) 6.9 Hz), 0.96 (t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 100
MHz) δ 177.9, 173.5, 171.2, 132.6, 126.1, 67.7, 61.5, 53.1, 48.6,
45.5, 44.8, 39.1, 38.6, 37.8, 32.6, 31.7, 31.3, 29.7, 29.0, 20.1, 19.8,
17.73, 17.4, 13.2; MS (ESI) m/z 515 (M + H+); HRMS calcd for
C24H42N4O4S2 (M + H+) 515.2720, found 515.2723; LC/MS
retention time [A] 11.88 min, [B] 22.65 min.
(11S,15R,17R,17aR,1′R,3′S)-12-(3-Butylcarbamoyl-1-hydroxy-
butyl)-15-methyl-14,17-dioxo-2,3,4,4a,6,9,11,12,13,14,15,16,17,-
17a-tetradecahydro-5,10-dithia-1,13,16-triaza-benzocyclopen-
tadecene-1-carboxylic Acid tert-Butyl Ester (51) and (11S,15R,-
17S,17aS,1′R,3′S)-12-(3-Butylcarbamoyl-1-hydroxy-butyl)-15-
methyl-14,17-dioxo-2,3,4,4a,6,9,11,12,13,14,15,16,17,17a-tetra-
decahydro-5,10-dithia-1,13,16-triaza-benzocyclopentadecene-1-
carboxylic Acid tert-Butyl Ester (53). Into a solution of dry liquid
ammonia (300 mL) was added 50 (36 mg, 0.048 mmol); then
sodium was added portionwise until a blue color persisted for more
than 15 min. trans-1,4-Dibromo-2-butene was added. The mixture
was allowed to reflux for 2 h, and then ammonia was removed
with a stream of argon. The residue was dissolved in AcOEt,
sequentially washed with 10% citric acid, then with brine, dried
over NaSO4, and concentrated. Flash chromatography (4% MeOH
in AcOEt) of the residue gave a mixture of 51 and 53, which were
separated by preparative HPLC to give 51 (8 mg, 27%) and 53 (8
4-Trifluoromethanesulfonyloxy-3,6-dihydro-2H-pyridine-1-
carboxylic Acid tert-Butyl Ester (56). Into a solution of diiso-
propylamine (0.78 mL, 5.6 mmol) in THF (15 mL) was added
n-BuLi (1.6 M in hexane, 3.5 mL, 5.4 mmol) at -10 °C. The
mixture was stirred at -10 to 0 °C for 30 min to get a LDA solution,
which was added dropwise to a solution of N-Boc-4-oxo-piperidine
55 (1.0 g, 4.9 mmol) in THF (5 mL) at -78 °C. After the mixture
was stirred for 2 h, N-(5-chloro-2-pyridyl)triflimide (2.17 g, 5.1
mmol) in THF (5 mL) was added dropwise. The mixture was stirred
at -78 °C for 12 h, then warmed to room temperature and
concentrated. Flash chromatography (hexane/AcOEt 2/1) of the
residue gave 56 (1.2 g, 81%): 1H NMR (CDCl3, 400 MHz) δ 5.75
1
mg, 27%). For 51: [R]D +112 (c 0.8, MeOH); H NMR (MeOD,
400 MHz) δ 5.81 (m, 1H), 5.66 (m, 1H), 4.87 (d, 1H, J ) 4.5 Hz),
4.58 (q, 1H, J ) 6.8 Hz), 3.94 (m, 1H), 3.87 (m, 1H), 3.61 (dt,
1H, J ) 9.7, 3.2 Hz), 3.50 (dd, 1H, J ) 14.7, 5.7 Hz), 3.36 (m,
1H), 3.33 (m, 1H), 3.22 (dd, 1H, J ) 13.6, 7.8 Hz), 3.19 (t, 2H, J
) 7.0 Hz), 3.11 (dd, 1H, J ) 13.5, 7.9 Hz), 3.02 (m, 1H), 2.91
(dd, 1H, J ) 14.2, 6.1 Hz), 2.61 (m, 1H), 2.52 (dd, 1H, J ) 14.2,
7.9 Hz), 1.87 (m, 1H), 1.74 (m, 4H), 1.52-1.43 (m, 2H), 1.49 (s,
9H), 1.41 (d, 3H, J ) 6.9 HZ), 1.36 (m, 3H), 1.14 (d, 3H, J ) 7.0
Hz), 0.96 (t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz) δ
177.9, 173.5, 169.9, 156.0, 131.0, 128.8, 80.9, 69.5, 53.5, 49.7,
49.1, 45.9, 39.1, 38.8, 37.7, 33.9, 32.8, 32.7, 31.6, 27.7, 27.0, 24.2,
20.1, 18.0, 16.6, 13.1; MS (ESI) m/z 637 (M + Na+); HRMS calcd
for C29H50N4O6S2 (M + H+) 615.3244, found 615.3241; LC/MS
retention time [A] 23.52 min, [B] 8.38 min. For 53: [R]D -90.5 (c
0.4, MeOH); 1H NMR (MeOD, 400 MHz) δ 5.6 (m, 2H), 4.33 (m,
2H), 4.22 (b, 1H), 3.90 (m, 1H), 3.81 (m, 1H), 3.68 (m, 1H), 3.49
(m, 3H), 3.19 (t, 2H, J ) 7.0 Hz), 3.07 (m, 2H), 3.0 (m, 1H), 2.92
(m, 1H), 2.62 (m, 1H), 2.34 (m, 1H), 2.06 (m, 1H), 1.78 (m, 3H),
(b, 1H), 4.03 (b, 2H), 3.62 (m, 2H), 2.43 (b, 2H), 1.46 (s, 9H); 13
C
NMR (CDCl3, 100 MHz) δ 154.7, 149.8, 139.8, 80.9, 60.7, 41.8,
28.7, 28.5, 21.4.
3,6-Dihydro-2H-pyridine-1,4-dicarboxylic Acid 1-tert-Butyl
Ester 4-Methyl Ester (57). Into a solution of 56 (0.26 g, 0.78
mmol) in DMF (3.2 mL) and MeOH (1.5 mL) were added
palladium acetate (5 mg, 0.03 mmol), triphenylphosphine (13 mg,
0.06 mmol), and triethylamine (0.22 mL, 1.56 mmol). The mixture
was purged with CO for 5 min and then stirred under CO
atmosphere (with a balloon) at room temperature for 12 h. Ether
(20 mL) and H2O (5 mL) were added; the organic layer was washed
with H2O until neutral, dried over Na2SO4, and concentrated. Flash
chromatography (hexane/AcOEt 5/1) of the residue gave 57 (146

4560 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
mg, 77%): 1H NMR (CDCl3, 400 MHz) δ 6.82 (b, 1H), 4.01 (b,
2H), 3.45 (t, 2H, J ) 5.55 Hz), 2.33 (b, 2H), 1.41 (s, 9H); 13C
NMR (CDCl3, 100 MHz) δ 164.5, 154.6, 134.5, 131.1, 80.652.1,
43.8, 40.5, 28.7, 24.6.
37.7, 37.2, 36.8, 35.3, 32.2, 31.2, 27.2, 24.0, 19.6, 17.1, 16.9, 12.9,
12.7; MS (FAB) m/z 743 (M + H+), 643, 154; HRMS calcd for
C39H58N4O6S2 (M + H+) 743.3876, found 743.3872.
(4R,7R,10S,18S,1′R,3′S)-10-(3-Butylcarbamoyl-1-hydroxy-bu-
tyl)-7-methyl-5,8-dioxo-1,3,4,4a,5,6,7,8,9,10,11,13,16,17a-tet-
radecahydro-12,17-dithia-2,6,9-triaza-benzocyclopentadecene-
2-carboxylic Acid tert-Butyl Ester (62). Compound 62 (9 mg,
39%) was prepared from 61 (28 mg, 0.038 mmol) and trans-1,4-
dibromo-2-butene (32 mg, 0.1 mmol) according to the procedure
for the preparation of 23: [R]D +133.3 (c 0.45, MeOH); 1H NMR
(MeOD, 400 MHz) δ 5.72 (m, 1H), 5.33 (m, 1H), 4.53 (m, 1H),
4.20 (m, 2H), 3.85 (m, 2H), 3.45 (m, 2H), 3.17 (m, 5H), 2.92 (m,
3H), 2.66 (dd, 1H, J ) 14.4, 10.2 Hz), 2.57 (m, 1H), 2.49 (dd, 1H,
J ) 14.4, 3.2 Hz), 1.67 (m, 2H), 1.51 (m, 2H), 1.47 (s, 9H), 1.37
(m, 2H), 1.348 (d, 3H, J ) 7.0 Hz), 1.13 (d, 3H, J ) 7.0 Hz), 0.94
(t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz) δ 178.0, 176.4,
173.7, 156.0, 132.7, 126.0, 80.0, 67.4, 53.0, 47.1, 45.9, 42.4, 39.2,
39.1, 38.7, 37.9, 32.4, 31.7, 31.2, 29.3, 27.7, 22.4, 20.1, 17.7, 17.4,
13.5, 13.1; MS (FAB) m/z 615 (M + H+), 515, 442, 307; IR
(CHCl3) 3299, 1734, 1634, 1536; HRMS calcd for C29H50N4O6S2
(M + H+) 615.3250, found 615.3227; LC/MS retention time [A]
22.77 min.
cis-3-Benzylsulfanyl-piperidine-1,4-dicarboxylic Acid 1-tert-
Butyl Ester 4-Methyl Ester (58). Into a solution of 57 (96 mg,
0.37 mmol) in MeOH (2.8 mL) was added benzyl mercaptan (0.14
mL, 1.1 mmol). A solution of NaOMe in MeOH (0.5 M, 2.0 mL)
was added dropwise. The mixture was stirred at room temperature
for 2 h until the reaction was complete, then Amberlite IR 120(+)
was added to pH 7, the resin was filtered and washed with MeOH,
and the filtrate was concentrated. Flash chromatography (hexane/
AcOEt 5/1) of the residue gave 58 (0.12 g, 89%): 1H NMR (CDCl3,
400 MHz) δ 7.34-7.23 (m, 5H), 4.02 (m, 2H), 3.74 (ab, 2H, J )
13.5 Hz), 3.63 (s, 3H), 3.12 (dd, 1H, J ) 13.6, 2.55 Hz), 3.05 (m,
1H), 2.85 (td, 1H, J ) 13.4, 3.0 Hz), 2.72 (dt, 1H, J ) 10.6, 4.1
Hz), 1.86 (m, 1H), 1.70 (m, 1H), 1.49 (s, 9H); 13C NMR (CDCl3,
100 MHz) δ 172.8, 155.4, 138.3, 129.4, 128.8, 127.5, 80.1, 52.2,
47.4, 45.7, 43.0, 42.7, 36.3, 28.9, 24.5; MS (FAB) m/z 365 (M +
H+); HRMS calcd for C19H27NO4S (M + H+) 365.1647, found
365.1645.
(3S,4R)-3-Benzylsulfanyl-piperidine-1,4-dicarboxylic Acid 1-tert-
Butyl Ester 4-Methyl Ester (59) and (3R,4S)-3-Benzylsulfanyl-
piperidine-1,4-dicarboxylic Acid 1-tert-Butyl Ester (60). Com-
pound 58 (72 mg, 0.4 mmol) was dissolved in acetone (0.2 mL),
and then phosphate buffer (pH 7.2, 4.0 mL) was added. To this
solution were added pig liver esterase (14 mg) and 0.1 N NaOH to
pH 8. The mixture was stirred at room temperature for 4 days with
occasionally addition of 0.1 N NaOH to maintain pH 8. HCl (1 N)
was added to pH 2, the mixture was extracted with AcOEt (3 × 20
mL), and the combined organic layers were washed with brine,
dried over Na2SO4, and concentrated. Flash chromatography
(hexane/AcOEt 5/1, pure AcOEt) of the residue gave 59 (35 mg,
49%) and 60 (32 mg, 49%). For 59: [R]D -92.2 (c 1.8, CHCl3);
1H NMR (CDCl3, 400 MHz) δ 7.34-7.23 (m, 5H), 4.02 (m, 2H),
3.74 (ab, 2H, J ) 13.5 Hz), 3.63 (s, 3H), 3.12 (dd, 1H, J ) 13.6,
2.55 Hz), 3.05 (m, 1H), 2.85 (td, 1H, J ) 13.4, 3.0 Hz), 2.72 (dt,
1H, J ) 10.6, 4.1 Hz), 1.86 (m, 1H), 1.70 (m, 1H), 1.49 (s, 9H);
13C NMR (CDCl3, 100 MHz) δ 172.8, 155.4, 138.3, 129.4, 128.8,
127.5, 80.1, 52.2, 47.4, 45.7, 43.0, 42.7, 36.3, 28.9, 24.5; MS (FAB)
m/z 365 (M + H+); HRMS calcd for C19H27NO4S (M + H+)
365.1647, found 365.1645. For 60: [R]D +65.4 (c 1.5, CHCl3); 1H
NMR (CDCl3, 400 MHz) δ 7.34-7.23 (m, 5H), 4.08 (m, 2H), 3.81
(ab, 2H, J ) 13.1 Hz), 3.14 (m, 2H), 3.08 (bs, 1H), 2.80 (m, 2H),
1.65 (m, 2H), 1.48 (s, 9H); 13C NMR (CDCl3, 100 MHz) δ 177.5,
156.4, 138.2, 129.4, 128.9, 127.5, 80.3, 47.6, 45.7, 43.1, 42.9, 36.8,
28.8, 24.3; MS (FAB) m/z 352 (M + H+); IR (CHCl3) 2975, 1736,
1695, 1427, 1163.
(2S,4R,4′R,7′R,10′S,18′S)-N-Butyl-4-hydroxy-2-methyl-4-(7-
methyl-5,8-dioxo-1,3,4,4a,5,6,7,8,9,10,11,13,16,17a-tetradecahy-
dro-2H-12,17-dithia-2,6,9-triaza-benzocyclopentadecen-10-yl)-
butyramide (63). Compound 63 (6.6 mg, quant) was prepared from
62 (8 mg, 0.013 mmol) according to the procedure for the
1
preparation of 52: [R]D +190 (c 0.3, MeOH); H NMR (MeOD,
400 MHz) δ 5.69 (m, 1H), 5.49 (m, 1H), 4.51 (m, 1H), 4.35 (dd,
1H, J ) 14.2, 7.2 Hz), 3.79 (m, 1H), 3.58 (m, 1H), 3.48 (m, 1H),
3.23-3.08 (m, 6H), 2.96 (dd, 1H, J ) 13.7, 10.3 Hz), 2.86 (dt,
1H, J ) 12.8, 3.4 Hz), 2.77 (td, 1H, J ) 12.9, 3.4 Hz), 2.59 (m,
1H), 2.43 (dd, 1H, J ) 13.6, 3.8 Hz), 1.94 (m, 1H), 1.82 (m, 1H),
1.68 (m, 1H), 1.52 (m, 2H), 1.46-1.26 (m, 5H), 1.38 (d, 3H, J )
7.1 Hz), 1.12 (d, 3H, J ) 7.0 Hz), 0.94 (t, 3H, J ) 7.3 Hz); 13C
NMR (MeOD, 100 MHz) δ 177.9, 174.0, 173.5, 130.4, 128.0, 67.8,
55.7, 50.4, 49.2, 46.8, 44.4, 43.5, 39.1, 39.0, 37.8, 33.5, 32.2, 31.7,
30.9, 22.6, 20.1, 18.0, 15.8, 13.1; MS (ESI) m/z 515 (M + H+);
HRMS calcd for C24H42N4O4S2 (M + H+) 515.2726, found
515.2743; LC/MS retention time [A] 12.65 min, [B] 20.72 min.
3,6-Dihydro-2H-pyridine-1,4-dicarboxylic Acid 1-tert-Butyl
Ester 4-Ethyl Ester (64). 1-Benzyl-3-oxo-piperidine-4-carboxylic
acid ethyl ester hydrochloric salt (3.0 g, 10 mmol) was dissolved
in an aqueous solution of EtOH-H2O (1/1, 20 mL). Pd/C (10%,
0.5 g) was added, and the mixture was charged with H2 to 50 psi,
stirred for 20 h, then filtered through a pad of Celite, and washed
with EtOH. The filtrate was concentrated under reduced pressure
to give a pale yellowish solid, which was dissolved in CHCl3 (15
mL). A solution of NaHCO3 (0.84 g, 10 mmol) in H2O (7.5 mL)
was added, followed by NaCl (1.71 g). The mixture was heated to
70 °C, and a solution of (Boc)2O in CHCl3 (6 mL) was added slowly
by a syringe pump during a period of 3 h. The stirring was continued
for 8 h at 70 °C, then 2 h at room temperature. The organic layer
was separated, and the aqueous layer was extracted twice with
CHCl3. The combined organic layers were dried over MgSO4 and
concentrated. Flash chromatography (hexane/AcOEt 5/1) of the
residue gave 3-oxo-piperidine-1,4-dicarboxylic acid 1-tert-butyl
ester 4-ethyl ester (2.2 g, 81%). Into a solution of the former ester
(0.27 g, 1 mmol) in EtOH (5 mL), NaBH4 (25 mg, 0.6 mmol) was
added portionwise. The mixture was stirred at room temperature
for 3 h, and the solvent was removed. The residue was diluted with
AcOEt, washed sequentially with 1 N HCl, then with brine, dried
over Na2SO4, and concentrated. Flash chromatography (hexane/
AcOEt 2/1) of the residue gave 3-hydroxy-piperidine-1,4-dicar-
boxylic acid 1-tert-butyl ester 4-ethyl ester as a mixture of cis and
trans isomers with a ratio of 4/1 (0.26 g, 96%). Into this mixture
(0.16 g, 0.6 mmol) in CH2Cl2 (9 mL) was added ADDP (0.3 g, 0.9
mmol) and imidazole (84 mg, 0.9 mmol). PMe3 (1 M in toluene,
1.2 mL) was then added dropwise. The mixture was stirred at room
temperature for 1 day, and hexane (9 mL) was added. The solid
was filtered off, and the residue was washed once with hexane.
(3S,4R,1′R,1′′S,2′′R,4′′S)-3-Benzylsulfanyl-4-[1-(1-benzylsul-
fanylmethyl-4-butylcarbamoyl-2-hydroxy-pentylcarbamoyl)-
ethylcarbamoyl]-piperidine-1-carboxylic Acid tert-Butyl Ester
(61). Into a solution of 60 (22 mg, 0.063 mmol) and 5-(2-amino-
propionylamino)-6-benzylsulfanyl-4-hydroxy-2-methyl-hexanoic acid
butylamide (prepared separately, 26 mg, 0.063 mmol) in CH2Cl2
(2.5 mL) were added PyBOP (49 mg, 0.095 mmol) and DIEA (24
µL, 0.13 mmol) at 0 °C. The mixture was stirred at 0 °C to room
temperature for 4 h, and then 10% citric acid (1 mL) was added.
The mixture was extracted with AcOEt (3 × 10 mL), and the
combined organic layers were sequentially washed with saturated
NaHCO3, then with brine, dried over Na2SO4, and concentrated to
give a mixture of two diastereoisomers, which were separated by
flash chromatography (4% MeOH in AcOEt), giving 61 (32 mg,
1
68%): [R]D -7.5 (c 0.5, MeOH); H NMR (MeOD, 400 MHz) δ
7.36-7.19 (m, 10H), 4.36 (m, 1H), 3.96 (m, 3H), 3.77 (m, 3H),
3.69 (ab, 2H, J ) 13.1 Hz), 3.25 (m, 1H), 3.17 (m, 3H), 2.90 (m,
1H), 2.79 (m, 1H), 2.62 (dd, 1H, J ) 13.6, 7.0 Hz), 2.55 (m, 1H),
2.47 (dd, 1H, J ) 13.6, 7.6 Hz), 1.90 (m, 1H), 1.68 (m, 2H), 1.50
(m, 2H), 1.47 (s, 9H), 1.38 (d, 3H, J ) 7.1 HZ), 1.32 (m, 4H),
1.11 (d, 3H, J ) 7.0 Hz), 0.93 (t, 3H, J ) 7.3 Hz); 13C NMR
(MeOD, 100 MHz) δ 177.4, 173.4, 1732.3, 155.2, 138.3, 128.8,
128.1, 127.9, 126.7, 126.4, 79.7, 68.3, 62.5, 60.0, 52.6, 49.3, 38.6,

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4561
The filtrate was concentrated, and the residue was purified by flash
chromatography (hexane/AcOEt 5/1, 2/1) to give 64 (0.12 g,
80%): 1H NMR (CDCl3, 400 MHz) δ 6.89 (s, 1H), 4.21 (q, 2H, J
) 7.1 Hz), 4.06 (d, 2H, J ) 2.8 Hz), 3.51 (t, 2H, J ) 5.6 Hz), 2.39
(bs, 2H), 1.46 (s, 9H), 1.29 (t, 3H, J ) 7.2 Hz); 13C NMR (CDCl3,
100 MHz) δ 166.74, 155.1, 135.5, 129.6, 80.4, 61.0, 43.9, 40.8,
28.8, 24.8, 14.7; MS (FAB+) m/z 255 (M + H+); IR (CHCl3) ν
(cm-1) 2973, 1701, 1418, 1247, 1168; HRMS calcd for C13H21-
NO4 (M + H+) 255.1471, found 255.1480.
3,6-Dihydro-2H-pyridine-1,4-dicarboxylic Acid 1-tert-Butyl
Ester 4-(2-Trimethylsilanyl-ethyl) Ester (65). Into a solution of
64 (85 mg, 0.33 mmol) in THF (0.5 mL) was added 1 N LiOH
(0.4 mL) at room temperature. The mixture was stirred overnight;
then 1 N HCl was added to pH 2, and the mixture was extracted
with AcOEt (3 × 10 mL). The combined organic layers were
washed with brine, dried over Na2SO4, and concentrated to give
an acid (74 mg, 98%). Into a solution of this acid (52 mg, 0.23
mmol) in CH2Cl2 (3 mL) were added EDCI (66 mg, 0.34 mmol),
trimethylsilyl ethanol (50 µL, 0.34 mmol), and 4-dimethylami-
nopyridine (DMAP; 42 mg, 0.34 mmol) at 0 °C. The mixture was
stirred at 0 °C to room temperature for 6 h until the reaction was
complete and then filtered through a pad of Celite and washed with
AcOEt, and the filtrate was concentrated. Flash chromatography
(hexane/AcOEt 7/1) of the residue gave pure 65 (55 mg, 74%):
1H NMR (CDCl3, 400 MHz) δ 6.86 (bs, 1H), 4.24 (t, 2H, J ) 8.4
Hz), 4.06 (m, 2H), 3.51 (t, 2H, J ) 5.6 Hz), 3.50 (t, 2H, J ) 5.6
Hz), 2.38 (m, 2H), 1.47 (s, 9H), 1.02 (t, 2H, J ) 8.4 Hz), 0.05 (s,
9H); 13C NMR (CDCl3, 100 MHz) δ 166.8, 155.1, 135.3, 129.8,
80.4, 63.3, 44.0, 39.7, 28.8, 24.8, 17.7, -1.0; MS (FAB) m/z 328
(M + H+); HRMS calcd for C16H30NO4Si (M + H+) 328.1944,
found 328.1939.
cis-3-Benzylsulfanyl-piperidine-1,4-dicarboxylic Acid 1-tert-
Butyl Ester 4-(2-Trimethylsilanyl-ethyl) Ester (66). Into a
solution of 65 (140 mg, 0.43 mmol) in MeOH (3 mL) was added
benzyl mercaptan (0.17 mL, 1.72 mmol), followed by a solution
of NaOMe in MeOH (0.5 M, 2.15 mL) added dropwise at 0 °C.
The mixture was stirred at 0 °C to room temperature for 2 h until
the reaction was complete; then Amberlite IR 120(+) was added
to pH 7, and the mixture was filtered and washed with MeOH.
The filtrate was concentrated, and the residue was purified by
flash chromatography (hexane/AcOEt 5/1) to give 66 (0.16 g,
82%): 1H NMR (CDCl3, 400 MHz) δ 7.34-7.23 (m, 5H), 4.21-
4.02 (m, 4H), 3.76 (ab, 2H, J ) 13.46 Hz), 3.14 (dd, 1H, J ) 13.6,
2.65 Hz), 3.08 (bs, 1H), 1.73 (m, 1H), 1.49 (s, 9H), 0.94 (t, 2H, J
) 8.6 Hz), 0.05 (s, 9H); 13C NMR (CDCl3, 100 MHz) δ 172.6,
155.4, 138.4, 129.4, 128.9, 127.5, 80.1, 63.4, 45.8, 43.0, 36.3, 28.9,
24.5, 17.7, -1.0; MS (FAB) m/z 452 (M + H+), 396, 368, 324,
278; HRMS calcd for C23H37NO4 (M + H+) 452.2290, found
452.2268.
(3R,4S,1′R,1′′S,2′′R,4′′S)-3-Benzylsulfanyl-4-[1-(1-benzylsul-
fanylmethyl-4-butylcarbamoyl-2-hydroxy-pentylcarbamoyl)-
ethylcarbamoyl]-piperidine-1-carboxylic Acid tert-Butyl Ester
(67). Into a solution of 66 (30 mg, 0.066 mmol) in THF (0.4 mL)
were added TBAF (1 N in THF, 0.1 mL) and molecular sieves 4
Å at 0 °C. The mixture was stirred at 0 °C to room temperature for
3 h, then 10% citric acid was added to pH 3.0, and the mixture
was extracted with AcOEt (3 × 10 mL). The combined organic
layers were washed sequentially with 10% citric acid, then with
brine, dried over Na2SO4, and concentrated to give 3-benzylsulfanyl-
piperidine-1,4-dicarboxylic acid 1-tert-butyl ester (23 mg, quant):
1H NMR (CDCl3, 400 MHz) δ 7.34-7.23 (m, 5H), 4.08 (m, 2H),
3.81 (ab, 2H, J ) 13.1 Hz), 3.14 (m, 2H), 3.08 (bs, 1H), 2.80 (m,
2H), 1.65 (m, 2H), 1.48 (s, 9H); 13C NMR (CDCl3, 100 MHz) δ
177.5, 156.4, 138.2, 129.4, 128.9, 127.5, 80.3, 47.6, 45.7, 43.1,
42.9, 36.8, 28.8, 24.3; MS (FAB+) m/z 352 (M + H+); IR (CHCl3)
2975, 1736, 1695, 1427, 1163; MS (ESI) m/z 352 (M + H+). Into
a solution of the above acid (22 mg, 0.063 mmol) and the amine
derived from 21 (26 mg, 0.063 mmol) in CH2Cl2 (2.5 mL) were
added PyBOP (49 mg, 0.095 mmol) and DIEA (24 µL, 0.13 mmol)
at 0 °C. The mixture was stirred at 0 °C to room temperature for
4 h, and then 10% citric acid (1 mL) was added. The mixture was
extracted with AcOEt (3 × 10 mL); the combined organic layers
were washed sequentially with saturated NaHCO3, then with brine,
dried over Na2SO4, and concentrated to give a mixture of two
diastereoisomers, which were separated by flash chromatography
(4% MeOH in AcOEt) to give 67 (16 mg, 34%): [R]D -22.8 (c
0.9, MeOH); 1H NMR (MeOD, 400 MHz) δ 7.36-7.20 (m, 10H),
4.30 (dd, 1H, J ) 14.3, 7.1 Hz), 4.05 (m, 1H), 3.92 (m, 2H), 3.77
(s, 2H), 3.74 (m, 1H), 3.72 (s, 2H), 3.25 (d, 1H, J ) 12.8 Hz),
3.16 (t, 2H, J ) 6.6 Hz), 2.93 (m, 2H), 2.77 (m, 1H), 2.60 (dd,
1H, J ) 13.8, 7.1 Hz), 2.53 (m, 1H), 2.47 (dd, 1H, J ) 13.7, 7.6
Hz), 2.0 (m, 1H), 1.64 (m, 2H), 1.49 (s, 9H), 1.36 (m, 4H), 1.30
(d, 3H, J ) 7.0 HZ), 1.10 (d, 3H, J ) 7.0 Hz), 0.93 (t, 3H, J ) 7.3
Hz); 13C NMR (MeOD, 100 MHz) δ 178.0, 174.2, 173.7, 155.8,
138.8, 138.6, 129.4, 129.2, 128.6, 128.4, 127.2, 126.9, 80.2, 71.9,
68.7, 60.5, 52.6, 49.7, 45.9, 43.7, 39.2, 39.0, 38.3, 37.7, 35.7, 32.6,
31.7, 27.7, 24.3, 20.1, 19.9, 17.7, 17.2, 13.5, 13.2; MS (FAB) m/z
743 (M + H+), 643, 154; IR (CHCl3) 2968, 1710, 1654, 14367,
942; HRMS calcd for C39H58N4O6S2 (M + H+) 743.3876, found
743.3872.
(4S,7R,10S,18R,1′R,3′S)-10-(3-Butylcarbamoyl-1-hydroxy-bu-
tyl)-7-methyl-5,8-dioxo-1,3,4,4a,5,6,7,8,9,10,11,13,16,17a-tet-
radecahydro-12,17-dithia-2,6,9-triaza-benzocyclopentadecene-
2-carboxylic Acid tert-Butyl Ester (68). Into a solution of dry
liquid ammonia (300 mL) was added 67 (36 mg, 0.048 mmol);
then sodium was added portionwise until a blue color persisted for
5-10 min. trans-1,4-Dibromo-2-butene (35 mg, 0.16 mmol) was
added. The mixture was allowed to reflux for 2 h, and then ammonia
was removed with a stream of argon. The residue was dissolved in
AcOEt, sequentially washed with 10% citric acid and with brine,
dried over Na2SO4, and concentrated. Flash chromatography (4%
MeOH in AcOEt) of the residue gave 68 (12 mg, 48%): [R]D -80
1
(c 0.11, MeOH); H NMR (MeOD, 400 MHz) δ 7.87 (m, 1H),
7.71 (bs, 1H), 5.71 (m, 1H), 5.51 (m, 1H), 4.33 (m, 2H), 4.24 (m,
2H), 3.80 (m, 1H), 3.45 (m, 2H), 3.22-3.03 (m, 7H), 2.83 (m,
2H), 2.59 (m, 1H), 2.36 (d, 1H, J ) 8.23 Hz), 1.90 (m, 1H), 1.67
(m, 2H), 1.52 (m, 2H), 1.47 (s, 9H), 1.38 (d, 3H, J ) 7.1 HZ),
1.33 (m, 2H), 1.11 (d, 3H, J ) 7.0 Hz), 0.94 (t, 3H, J ) 7.3 Hz);
13C NMR (MeOD, 100 MHz) δ 178.0, 174.2, 174.0, 156.0, 130.0,
123.8, 80.2, 67.7, 60.2, 56.3, 50.5, 45.3, 44.5, 39.8, 39.3, 37.8, 33.7,
32.1, 31.7, 27.7, 22.7, 20.1, 18.1, 15.8, 13.2; MS (FAB) m/z 615
(M + H+); IR (CHCl3) 3286, 1644, 1623, 1542; HRMS calcd for
C29H50N4O6S2 (M + H+) 615.3250, found 615.3246; LC/MS
retention time [A] 21.57 min, [B] 29.00 min.
(2S,4R,4′S,7′R,10′S,18′R)-N-Butyl-4-hydroxy-2-methyl-4-(7-
methyl-5,8-dioxo-1,3,4,4a,5,6,7,8,9,10,11,13,16,17a-tetradecahy-
dro-2H-12,17-dithia-2,6,9-triaza-benzocyclopentadecen-10-yl)-
butyramide (69). Into a solution of 68 (6 mg, 0.009 mmol) in
CH2Cl2 (3 mL) was added TFA (0.6 mL). The mixture was stirred
at room temperature for 30 min and concentrated under vacuum.
The residue was treated with AcOEt (10 mL), washed with saturated
NaHCO3 (1 mL), dried over Na2SO4, and concentrated to give 69
1
(4.2 mg, quant): [R]D -58.7 (c 0.3, MeOH); H NMR (MeOD,
400 MHz) δ 5.74 (m, 1H), 5.34 (m, 1H), 4.51 (m, 1H), 4.34 (m,
1H), 4.22 (m, 2H), 3.86 (m, 2H), 3.17 (m, 3H), 2.96 (m, 2H), 2.70-
2.34 (m, 3H), 1.71 (m, 3H), 1.54-1.34 (m, 12H), 1.14 (d, 3H, J )
6.9 Hz), 0.94 (t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz) δ
178.6, 177.9, 168.3, 131.4, 128.9, 68.1, 67.5, 45.0, 39.2, 39.1, 31.7,
30.6, 29.4, 29.1, 23.9, 23.0, 20.1, 17.3, 13.4, 13.1; MS (ESI) m/z
515 (M + H+); HRMS calcd for C24H42N4O4S2 (M + H+)
515.2726, found 515.2743; LC/MS retention time [A] 12.77 min,
[B] 6.08 min.
cis-Piperidine-1,2,3-tricarboxylic Acid 1-tert-Butyl Ester 2-
Methyl Ester (70). Furo[3,4-b]pyridine-5,7-dione (12 g, 80.4 mmol)
was dissolved in boiling methanol (60 mL), and the mixture was
refluxed for 2 h. After cooling, the solvent was removed, and the
solid was recrystallized in ethyl acetate to give pyridine-2,3-
dicarboxylic acid 2-methyl ester (7 g, 50%). Into a flask with this
ester (3 g, 16.6 mmol) were added acetic acid (30 mL) and 10%
Pd/C (0.9 g); then H2 was charged in to 50 psi, and the mixture
was stirred for 16 h and then filtered through a pad of Celite. The
filtrate was concentrated to dryness under reduced pressure. The

4562 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
residue was dissolved in methanol (60 mL); then NaHCO3 (3.5 g,
44.4 mmol) and Boc2O (4 g, 18.3 mmol) were added consecutively.
The mixture was placed into an ultrasonic bath for 3 h. The solid
was filtered off, the filtrate was concentrated, and the residue was
purified by flash chromatography (hexane/AcOEt 2/1) to give
racemic 70 (3.6 g, 76%): 1H NMR (CDCl3, 400 MHz) δ 9.9 (s,
1H), 5.6, 5.3 (b, 1H), 4.13-3.94 (m, 1H), 3.72 (s, 3H), 2.66 (m,
2H), 1.68 (m, 4H), 1.48 (s, 9H); 13C NMR (CDCl3, 100 MHz) δ
177.6, 170.7, 156.6, 80.7, 52.8, 43.4, 28.7, 24.4, 22.6; MS (ESI)
m/z 288 (M + H+); HRMS calcd for C13H21NO6 (M + H+)
288.1442, found 288.1435.
cis-3-Formyl-piperidine-1,2-dicarboxylic Acid 1-tert-Butyl
Ester 2-Methyl Ester (71). Into a solution of 70 (1.3 g, 4.5 mmol)
in toluene (25 mL) was added oxalyl chloride (0.41 mL, 4.5 mmol),
followed by DMF (8 µL) at 0 °C. The mixture was stirred at 0 °C
for 1 h and then concentrated to dryness. The residue was dissolved
in THF (25 mL), and sodium borohydride (0.17 g, 4.5 mmol) was
added portionwise at 0 °C. After the mixture was stirred for another
30 min, water (7 mL) was added carefully, followed by AcOEt
(20 mL). The organic phase was separated, and the aqueous layer
was extracted once again with AcOEt (20 mL). The combined
organic layers were washed with brine, dried over Na2SO4, and
concentrated. Flash chromatography (hexane/AcOEt 1/2) of the
residue gave the alcohol (0.96 g, 78%). Into a solution of this
alcohol (0.83 g, 3.0 mmol) in CH2Cl2 (30 mL) was added Dess-
Martin periodinane (1.6 g, 3.6 mmol) portionwise at 5 °C. The
mixture was stirred at room temperature overnight; then saturated
NaHCO3 (5 mL) and Na2S2O3 (10 mL) were added. The mixture
was then extracted with CH2Cl2 (3 × 30 mL). The combined
organic layers were washed with brine, dried over Na2SO4, and
concentrated. Flash chromatography of the residue (hexane/AcOEt
1/1) gave racemic 71 (0.73 g, 90%): 1H NMR (CDCl3, 400 MHz)
δ 9.71 (s, 1H), 5.56, 5.30 (d, 1H, J ) 4.4 Hz), 4.0 (m, 1H), 3.68
(s, 3H), 2.81 (m, 1H), 2.47 (m, 1H), 2.11 (m, 1H), 1.75 (m, 1H),
1.45 (s, 9H), 1.44-1.28 (m, 2H); 13C NMR (CDCl3, 100 MHz) δ
199.1, 170.2, 155.2, 80.6, 55.7, 52.3, 41.9, 28.1, 23.8, 20.5; MS
(ESI) m/z 272 (M + H+); HRMS calcd for C13H21NO5 (M + H+)
272.1493, found 272.1497.
cis-3-[2-(2-Trimethylsilanyl-ethoxycarbonyl)-ethyl]-piperidine-
1,2-dicarboxylic Acid 1-tert-Butyl Ester 2-Methyl Ester (72). Into
a solution of 71 (1.4 g, 5.2 mmol) in CH2Cl2 (40 mL) was added
Ph3PdCHCO2TMSE (3.45 g, 8.2 mmol). The mixture was stirred
at room temperature overnight and then concentrated. Flash
chromatography of the residue (hexane/AcOEt 5/1) gave a pure
ester (2.0 g, 93%). Into a flask containing this ester (1.9 g, 4.5
mmol), AcOEt (40 mL), and 10% Pd/C (0.5 g), H2 was filled in to
50 psi; then the suspension was stirred for 2 h and filtered through
a pad of Celite. The filtrate was concentrated, and the residue was
purified by flash chromatography (hexane/AcOEt 5/1) to give
racemic 72 (1.84 g, 98%): 1H NMR (CDCl3, 400 MHz) δ 4.87,
4.67 (s, 1H), 4.17 (t, 2H, J ) 8.4 Hz), 3.94 (m, 1H), 3.70 (s, 3H),
3.27 (m, 1H), 2.42 (m, 2H), 1.78-1.62 (m, 5H), 1.45 (s, 9H), 1.40
(m, 2H), 1.0 (t, 2H, J ) 8.4 Hz), 0.05 (s, 9H); 13C NMR (CDCl3,
100 MHz) δ 173.9, 172.0, 156.5, 80.6, 63.0, 58.2, 56.6, 51.9, 40.9,
32.5, 28.8, 26.0, 25.1, 17.7, -1.0; MS (ESI) m/z 416 (M + H+);
HRMS calcd for C20H37NO6Si (M + H+) 416.2463, found
416.2451.
cis-3-(2-Carboxy-ethyl)-piperidine-1,2-dicarboxylic Acid 1-tert-
Butyl Ester 2-Methyl Ester (73). To a solution of 72 (1.8 g, 4.3
mmol) in THF (26 mL) containing molecular sieves was added
TBAF (1 M in THF, 7 mL, 7 mmol) dropwise at 0 °C. The mixture
was stirred at 0 °C to room temperature for 5 h, 1 N HCl was
added to pH 2, and the mixture was extracted with AcOEt (3 × 30
mL). The combined organic layers were washed with brine, dried
over Na2SO4, and concentrated, and the residue was purified by
flash chromatography (hexane/AcOEt 1/2) to give racemic 73 (1.3
g, 93%): 1H NMR (CDCl3, 400 MHz) δ 9.6 (b, 1H), 4.85, 4.66 (s,
1H), 3.92 (m, 1H), 3.68 (s, 3H), 3.24 (m, 1H), 2.45 (m, 2H), 1.80-
1.61 (m, 5H), 1.42 (s, 9H), 1.33 (m, 2H); MS (ESI) m/z 316 (M +
H+); HRMS calcd for C15H25NO6 (M + H+) 316.1755, found
316.1748.
cis-3-(3-Oxo-propyl)-piperidine-1,2-dicarboxylic Acid 1-tert-
Butyl Ester 2-Methyl Ester (74). Racemic 74 (0.9 g, 86%) was
prepared from 73 (1.25 g, 3.9 mmol) as described for the preparation
of 71: 1H NMR (CDCl3, 400 MHz) δ 9.8 (s, 1H), 4.86, 4.66 (s,
1H), 3.92 (m, 1H), 3.70 (s, 3H), 3.16 (m, 1H), 2.49 (m, 2H), 1.80-
1.60 (m, 5H), 1.44 (s, 9H), 1.32 (m, 2H); MS (ESI) m/z 322 (M +
Na+); HRMS calcd for C15H25NO5 (M + Na+) 322.1615, found
322.1625.
cis-3-[4-(2-Trimethylsilanyl-ethoxycarbonyl)-but-3-enyl]-pi-
peridine-1,2-dicarboxylic Acid 1-tert-Butyl Ester 2-Methyl Ester
(75). Racemic 75 (1.08 g, 85%) was prepared from 74 (0.86 g,
2.88 mmol) according to the procedure for the preparation of 72:
1H NMR (CDCl3, 400 MHz) δ 6.93 (dt, 1H, J ) 15.4, 6.9 Hz),
5.82 (d, 1H, J ) 15.4 Hz), 4.86, 4.66 (s, 1H), 4.23 (t, 2H, J ) 8.5
Hz), 3.88 (m, 1H), 3.70 (s, 3H), 3.16 (m, 1H), 2.32 (m, 2H), 1.70
(m, 5H), 1.44 (s, 9H), 1.37 (m, 2H), 1.02 (t, 2H, J ) 8.5 Hz), 0.05
(s, 9H); 13C NMR (CDCl3, 100 MHz) δ 171.3, 166.3, 155.4, 147.9,
121.5, 79.9, 62.1, 55.9, 51.1, 41.1, 37.8, 31.1, 29.3, 28.0, 25.6, 24.7,
16.9, -1.8; MS (ESI) m/z 442 (M + H+); HRMS calcd for C22H39-
NO6Si (M + H+) 442.2619, found 442.2640.
cis-3-(4-Carboxy-but-3-enyl)-piperidine-1,2-dicarboxylic Acid
1-tert-Butyl Ester 2-Methyl Ester (76). To a solution of 75 (1.06
g, 2.4 mmol) in THF (20 mL) containing molecular sieves was
added TBAF (1 M in THF, 5 mL, 5 mmol) dropwise at 0 °C. The
mixture was stirred at 0 °C to room temperature for 5 h, 1 N HCl
was added to pH 2, and the mixture was extracted with AcOEt (3
× 20 mL). The combined organic layers were washed with brine,
dried over Na2SO4, and concentrated. The residue was purified by
flash chromatography (hexane/AcOEt 1/2) to give racemic 76 (0.74
g, 90%): 1H NMR (CDCl3, 400 MHz) δ 11.0 (b, 1H), 7.06 (dt,
1H, J ) 15.5, 7.0 Hz), 5.85 (d, 1H, J ) 15.7 Hz), 4.86, 4.67 (s,
1H), 3.90 (m, 1H), 3.70 (s, 3H), 3.14 (m, 1H), 2.34 (m, 2H), 1.68
(m, 5H), 1.45 (s, 9H), 1.33 (m, 2H); 13C NMR (CDCl3, 100 MHz)
δ 171.2, 170.9, 155.4, 150.9, 120.6, 79.9, 60.1, 57.3, 51.2, 41.1,
37.8, 31.0, 28.0, 25.7, 24.7, 20.7; MS (ESI) m/z 342 (M + H+);
HRMS calcd for C17H27NO6 (M + H+) 342.1911, found 342.1923.
cis-3-(5-Hydroxy-pent-3-enyl)-piperidine-1,2-dicarboxylic Acid
1-tert-Butyl Ester 2-Methyl Ester (77). Racemic 77 (0.14 g, 60%)
was prepared from 76 (0.245 g, 0.72 mmol) via reduction with
oxalyl chloride and NaBH4 following the preparation of 71, but
stopping at the alcohol stage: 1H NMR (CDCl3, 400 MHz) δ 5.64
(m, 2H), 4.86, 4.61 (s, 1H), 4.05 (m, 2H), 3.85 (m, 1H), 3.66 (s,
3H), 3.21 (m, 1H), 2.15 (m, 3H), 1.63 (m, 5H), 1.42 (s, 9H), 1.30
(m, 2H); 13C NMR (CDCl3, 100 MHz) δ 171.4, 155.3, 131.8, 129.4,
79.9, 63.1, 57.5, 51.0, 41.1, 37.8, 31.7, 28.0, 25.7, 24.7; MS (ESI)
m/z 328 (M + H+).
cis-3-(5-Hydroxy-pent-3-enyl)-piperidine-1,2-dicarboxylic Acid
1-tert-Butyl Ester (78). Into a solution of 77 (50 mg, 0.15 mmol)
in THF (1 mL) was added 1 N LiOH (0.7 mL, 0.7 mmol). The
mixture was stirred at room temperature for 40 h, and then 10%
citric acid was added to pH 2. The mixture was extracted with
AcOEt (3 × 20 mL). The combined organic layers were washed
with brine, dried over Na2SO4, and concentrated to give racemic
1
78 (48 mg, quant); H NMR (CDCl3, 400 MHz) δ 7.0 (b, 2H),
5.69 (m, 2H), 4.92, 4.66 (s, 1H), 4.11 (m, 2H), 3.89 (m, 1H), 3.21
(m, 1H), 2.11 (m, 23H), 1.68 (m, 5H), 1.46 (s, 9H), 1.29 (m, 2H);
13C NMR (CDCl3, 100 MHz) δ 176.1, 156.5, 133.1, 129.9, 81.0,
64.1, 56.5, 42.1, 32.4, 30.3, 28.8, 26.2, 25.5; MS (ESI) m/z 314
(M + H+).
(2R,3S,1′R,1′′S,2′′R,4′′S)-2-[1-(1-Benzylsulfanylmethyl-4-bu-
tylcarbamoyl-2-hydroxy-pentylcarbamoyl)-ethylcarbamoyl]-3-
(5-hydroxy-pent-3-enyl)-piperidine-1-carboxylic Acid tert-Butyl
Ester (79) and (2S,3R,1′R,1′′S,2′′R,4′′S)-2-[1-(1-Benzylsulfanyl-
methyl-4-butylcarbamoyl-2-hydroxy-pentylcarbamoyl)-ethyl-
carbamoyl]-3-(5-hydroxy-pent-3-enyl)-piperidine-1-carboxylic
Acid tert-Butyl Ester (80). Into a solution of 78 (48 mg, 0.15
mmol) and 5-(2-amino-propionylamino)-6-benzylsulfanyl-4-hy-
droxy-2-methyl-hexanoic acid butylamide (prepared separately, 74
mg, 0.18 mmol) in CH2Cl2 (5 mL) were added PyBOP (0.12 mg,
0.23 mmol) and DIEA (58 µL, 0.3 mmol) at 0 °C. The mixture
was stirred at 0 °C to room temperature for 4 h; then 10% citric

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4563
acid (1 mL) was added. The mixture was extracted with AcOEt (3
× 20 mL), and the combined organic layers were sequentially
washed with saturated NaHCO3, then with brine, dried over Na2-
SO4, and concentrated to give a mixture of two diastereoisomers
79 (34 mg, 32%) and 80 (34 mg, 32%), which were separated by
flash chromatography (4% MeOH in AcOEt). For 79: [R]D -47.5
0.96 (t, 3H, J ) 7.3 Hz); 13C NMR (CDCl3, 100 MHz) δ 177.2,
172.9, 171.2, 134.9, 124.6, 66.6, 61.2, 52.9, 44.1, 43.2, 38.3, 38.1,
37.0, 34.8, 31.7, 30.9, 28.8, 28.4, 25.7, 24.8, 19.4, 18.7, 16.8, 16.3;
MS (ESI) m/z 497 (M + H+); HRMS calcd for C25H44N4O4S (M
+ H+) 497.3156, found 497.3161; LC/MS retention time [A] 8.59
min, [B] 23.41min.
1
(c 0.75, MeOH); H NMR (CDCl3, 400 MHz) δ 7.36-7.23 (m,
(12S,15R,17S,17aR,1′R,3′S)-12-(3-Butylcarbamoyl-1-hydroxy-
butyl)-15-methyl-14,17-dioxo-3,4,4a,5,6,9,11,12,13,14,15,16,17,-
17a-tetradecahydro-2H-10-thia-1,13,16-triaza-benzocyclopen-
tadecene-1-carboxylic Acid tert-Butyl Ester (83). Compound 83
was obtained from 80 following the procedure for the preparation
5H), 5.66 (m, 2H), 4.62 (b, 1H), 4.41 (m, 2H), 4.0 (m, 2H), 3.94
(m, 2H), 3.88 (m, 1H), 3.78 (s, 2H), 3.18 (m, 2H), 2.60 (m, 3H),
2.20 (m, 2H), 1.69 (m, 6H), 1.53 (m, 4H), 1.48 (s, 9H), 1.39 (m,
8H), 1.12 (d, 3H, J ) 6.9 Hz), 0.95 (t, 3H, J ) 7.3 Hz); 13C NMR
(CDCl3, 100 MHz) δ 177.1, 173.6, 172.4, 156.3, 138.0, 128.4,
127.7, 126.2, 80.1, 67.0, 61.9, 57.5, 51.0, 49.0, 38.3, 37.6, 37.2,
36.9, 34.9, 32.4, 31.8, 30.9, 29.0, 27.0, 26.6, 24.4, 19.4, 17.6, 17.4,
12.4; MS (ESI) m/z 705 (M + H+); HRMS calcd for C37H60N4O7S
(M + H+) 705.4256, found 705.4253. For 80: [R]D -36.3 (c 0.95,
1
of 81: [R]D +36 (c 0.2, MeOH); H NMR (CDCl3, 400 MHz) δ
5.56 (m, 1H), 5.33 (m, 1H), 4.34 (m, 2H), 3.86 (m, 3H), 3.37 (m,
1H), 3.25-3.01 (m, 5H), 2.69 (dd, 1H, J ) 13.1, 10.3 Hz), 2.58
(m, 2H), 2.18 (m, 1H), 1.92 (m, 2H), 1.78-1.62 (m, 6H), 1.52-
1.30 (m, 8H), 1.47 (s, 9H),1.14 (d, 3H, J ) 7.0 Hz), 0.96 (t, 3H,
J ) 7.3 Hz); 13C NMR (CDCl3, 100 MHz) δ 179.1, 174.2, 173.6,
157.5, 137.0, 126.5, 81.9, 68.9, 61.4, 54.2, 51.2, 47.6, 40.3, 40.2,
39.9, 38.8, 37.6, 34.6, 34.1, 32.8, 31.1, 30.9, 28.8, 21.3, 18.7, 17.2,
14.3; MS (ESI) m/z 597 (M + H+); HRMS calcd for C30H52N4O6S
(M + H+) 597.3680, found 597.3679; LC/MS retention time [A]
13.72 min, [B] 31.69 min.
1
MeOH); H NMR (CDCl3, 400 MHz) δ 7.36-7.22 (m, 5H), 5.66
(m, 2H), 4.62 (b, 1H), 4.38 (m, 2H), 4.02 (m, 2H), 3.94 (m, 2H),
3.76 (m, 3H), 3.33 (m, 2H), 3.18 (t, 2H, J ) 7.0 Hz), 2.65-2.50
(m, 3H), 2.15 (m, 2H), 1.67 (m, 6H), 1.50 (m, 4H), 1.47 (s, 9H),
1.40 (m, 3H), 1.38 (d, 3H, J ) 7.0 Hz), 1.12 (d, 3H, J ) 6.9 Hz),
0.94 (t, 3H, J ) 7.3 Hz); 13C NMR (CDCl3, 100 MHz) δ 177.1,
173.4, 172.1, 156.2, 138.0, 130.8, 129.2, 128.4, 127.7, 126.2, 80.5,
67.2, 61.8, 59.5, 52.0, 38.3, 37.6, 37.2, 36.9, 34.9, 31.7, 30.9, 29.5,
29.0, 27.0, 26.9, 25.2, 24.6, 19.4, 16.9, 12.4; MS (ESI) m/z 705
(M + H+); HRMS calcd for C37H60N4O7S (M + H+) 705.4256,
found 705.4259.
(2R,4S,12′S,15′R,17′S,17a′R)-N-Butyl-4-hydroxy-2-methyl-4-
(15-methyl-14,17-dioxo-1,2,3,4,4a,5,6,9,11,12,13,14,15,16,17,17a-
hexadecahydro-10-thia-1,13,16-triaza-benzocyclopentadecen-12-
yl)-butyramide (84). Compound 84 was obtained from 83 following
the procedure for the preparation of 82: [R]D +18 (c 0.2, MeOH);
1H NMR (CDCl3, 400 MHz) δ 5.42 (m, 1H), 5.30 (m, 1H), 4.24
(m, 2H), 4.02 (m, 1H), 3.90 (m, 1H), 3.20 (m, 2H), 3.03 (m, 2H),
2.74 (m, 1H), 2.58 (m, 1H), 2.30 (m, 2H), 2.17 (m, 1H), 2.01 (m,
3H), 1.74 (m, 4H), 1.64 (m, 2H), 1.51 (m, 3H), 1.46 (d, 3H, J )
7.1 Hz), 1.40 (m, 3H), 1.15 (d, 3H, J ) 7.0 Hz), 0.96 (t, 3H, J )
7.3 Hz); 13C NMR (CDCl3, 100 MHz) δ 179.1, 176.5, 174.4, 137.1,
125.9, 68.3, 65.2, 61.2, 53.9, 49.9, 47.3, 40.2, 39.9, 38.9, 37.2, 33.8,
32.7, 31.1, 30.7, 28.5, 27.9, 21.3, 18.7, 18.0, 14.3; MS (ESI) m/z
497 (M + H+); HRMS calcd for C25H44N4O4S (M + H+) 497.3156,
found 497.3161.
(1′S)-[Pent-4-enyl-(1-phenyl-ethyl)-amino]-acetic Acid Methyl
Ester (85). Pent-4-enal (0.84 g, 10 mmol) was added to a solution
of (S)-1-phenyl-ethylamine (1.21 g, 10 mmol) and 4 Å molecular
sieves in CH2Cl2 (20 mL). The mixture was stirred at room
temperature for 3 h and then concentrated to dryness. The residue
was dissolved in methanol (40 mL) and cooled to 0 °C, NaBH4
(0.49 g, 13 mmol) was added portionwise, and the suspension was
stirred at 0 °C to room temperature for 30 min, then concentrated.
The residue was triturated with CH2Cl2, the solvent was removed
to give crude (S)-pent-4-enyl-(1-phenyl-ethyl)-amine, which was
dissolved in DMSO (200 mL), and methyl bromoformate (0.95 mL,
10 mmol) and triethylamine (1.66 mL, 12 mmol) were then added
consecutively. The mixture was stirred at room temperature for 40
h, then treated with a solution of saturated NH4Cl and NH4OH (2/
1, 50 mL) and extracted with ether (2 × 100 mL). The combined
extracts were washed with brine, dried over Na2SO4, and concen-
trated. Flash chromatography (hexane/AcOEt, 8/1) of the residue
gave 85 (0.74 g, 80%): [R]D -32.5 (c 1.0, CHCl3); 1H NMR
(CDCl3, 400 MHz) δ 7.40-7.24 (m, 5H), 5.79 (m, 1H), 4.95 (m,
2H), 4.05 (q, 1H, J ) 6.7 Hz), 3.69 (s, 3H), 3.38 (ab, 2H, J ) 17.2
Hz), 2.63 (m, 2H), 2.05 (m, 2H), 1.55 (m, 2H), 1.37 (d, 3H, J )
6.7 Hz); 13C NMR (CDCl3, 100 MHz) δ. 172.4, 144.2, 138.3, 127.8,
127.2, 126.5, 114.1, 60.0, 50.9, 50.2, 30.9, 26.6; MS (ESI) m/z
262 (M + H+); HRMS calcd for C16H23NO2 (M + H+) 262.1802,
found 262.1810.
(12S,15R,17R,17aS,1′R,3′S)-12-(3-Butylcarbamoyl-1-hydroxy-
butyl)-15-methyl-14,17-dioxo-3,4,4a,5,6,9,11,12,13,14,15,16,17,-
17a-tetradecahydro-2H-10-thia-1,13,16-triaza-benzocyclopen-
tadecene-1-carboxylic Acid tert-Butyl Ester (81). Sodium was
added portionwise to 79 (25 mg, 0.035 mmol) in liquid ammonia
(60 mL) at -78 °C until a permanent blue coloration was
established. After the mixture was stirred for another 15 min, the
color was discharged by addition of the minimum quantity of solid
NH4Cl, and the solvent was evaporated under a stream of argon.
The residue was dissolved in AcOEt (40 mL), washed sequentially
with 1 N HCl (3 mL) and then with brine, dried over Na2SO4, and
concentrated to give the free thiol (22 mg). Into a solution of this
thiol in CH2Cl2 (7 mL) were added 1,1′-(azodicarbonyl)dipiperidine
(ADDP) (18.5 mg, 0.07 mmol) and imidazole (5.0 mg, 0.07 mmol).
Trimethylphosphine (1 M in toluene, 73 µL, 0.073 mmol) was then
added dropwise. The mixture was stirred at room temperature for
40 h and evaporated. Flash chromatography (4% MeOH in AcOEt)
of the residue gave 81 (8.4 mg, 42%): [R]D -46.5 (c 0.4, MeOH);
1H NMR (CDCl3, 400 MHz) δ 5.58 (m, 1H), 5.30 (m, 1H), 4.64-
4.43 (m, 3H), 3.91 (m, 2H), 3.78 (m, 1H), 3.48 (m, 1H), 3.19 (m,
3H), 3.0 (dd, 1H, J ) 12.7, 5.5 Hz), 2.60 (m, 3H), 2.15 (m, 2H),
1.73 (m, 5H), 1.48 (s, 9H), 1.53-1.37 (m, 6H), 1.34 (d, 3H, J )
6.8 Hz), 1.14 (d, 3H, J ) 6.9 Hz), 0.97 (t, 3H, J ) 7.3 Hz); 13C
NMR (CDCl3, 100 MHz) δ 179.2, 173.9, 173.6, 157.3, 137.4, 126.6,
80.2, 68.4, 59.7, 52.9, 49.0, 42.7, 39.8, 38.9, 38.7, 37.2, 32.8, 32.7,
30.9, 30.4, 28.8, 26.7, 26.0, 21.3, 18.7, 14.3; MS (ESI) m/z 597
(M + H+); HRMS calcd for C30H52N4O6S (M + H+) 597.3680,
found 597.3687; LC/MS retention time [A] 14.45 min, [B] 32.46
min.
(2S,4R,12′S,15′R,17′R,17a′S)-N-Butyl-4-hydroxy-2-methyl-4-
(15-methyl-14,17-dioxo-1,2,3,4,4a,5,6,9,11,12,13,14,15,16,17,17a-
hexadecahydro-10-thia-1,13,16-triaza-benzocyclopentadecen-12-
yl)-butyramide (82). Into a solution of 81 (8 mg, 0.013 mmol) in
CH2Cl2 (3 mL) was added TFA (0.5 mL), and the mixture was
stirred at room temperature for 40 min. The solvent and excess
TFA were removed under reduced pressure, and the residue was
treated with AcOEt (20 mL), washed sequentially with saturated
NaHCO3, then with brine, dried over Na2SO4, and concentrated to
(2R,3S,1′S)-3-But-3-enyl-1-(1-phenyl-ethyl)-piperidine-2-car-
boxylic Acid Methyl Ester (86). Into a solution of 85 (0.34 g, 1.3
mmol) in Et2O (15 mL) was added LDA (1 M in THF and hexane,
1.55 mL) at -70 °C. The mixture was stirred at -70 to -50 °C
for 40 min; then ZnBr2 (1 M in Et2O, 4.6 mL) was added. The
mixture was stirred at -40 °C to room temperature for 5 h and
cooled to -40 °C; then a suspension of CuCN (0.54 g, 6 mmol) in
THF (10 mL) was added. The mixture was stirred at -40 to -5
°C for 1 h and cooled to -40 °C, and then allylbromide (0.4 mL,
1
give 82 (6.5 mg, quant): [R]D +5.5 (c 0.4, MeOH); H NMR
(CDCl3, 400 MHz) δ 5.56 (m, 1H), 5.27 (m, 1H), 4.54 (dd, 1H, J
) 13.8, 6.8 Hz), 3.85 (m, 1H), 3.79 (m, 1H), 3.60 (d, 1H, J ) 3.2
Hz), 3.19 (m, 4H), 3.0 (m, 1H), 2.60 (m, 4H), 2.34 (m, 1H), 2.18
(m, 1H), 1.92 (m, 4H), 1.75 (m, 2H), 1.68 (m, 3H), 1.50 (m, 3H),
1.40 (m, 2H), 1.33 (d, 3H, J ) 7.0 Hz), 1.14 (d, 3H, J ) 6.9 Hz),

4564 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
4.7 mmol) was added. The mixture was stirred at -40 °C to room-
temperature overnight, treated with a solution of saturated NH4Cl
and NH4OH (2/1, 20 mL), and extracted with AcOEt (3 × 30 mL).
The combined organic layers were sequentially washed with
saturated NH4Cl, then with brine, dried over Na2SO4, and concen-
trated. Flash chromatography (hexane/AcOEt, 15/1) of the residue
gave 86 (0.26 g, 65%): [R]D -9.5 (c 1.6, CHCl3); 1H NMR (CDCl3,
400 MHz) δ 7.35-7.24 (m, 5H), 5.72 (m, 1H), 4.89 (m, 2H), 3.66
(q, 1H, J ) 6.6 Hz), 3.63 (s, 3H), 3.42 (d, 1H, J ) 5.1 Hz), 3.10
(td, 1H, J ) 11.7, 3.1 Hz), 2.91 (m, 1H), 2.01 (m, 2H), 1.80 (m,
2H), 1.58 (m, 2H), 1.48 (td, 1H, J ) 12.8, 3.9 Hz), 1.33 (d, 3H, J
) 6.6 Hz), 1.31-1.11 (m, 2H); 13C NMR (CDCl3, 100 MHz) δ.
173.1, 145.0, 138.1, 127.8, 127.6, 127.4, 126.8, 126.4, 114.3, 62.4,
61.7, 49.8, 42.2, 37.8, 31.7, 30.8, 25.4, 24.9, 20.7; MS (ESI) m/z
302 (M + H+); HRMS calcd for C19H27NO2 (M + H+) 302.2115,
found 302.2115.
(2R,3S,1′S)-3-(3-Oxo-propyl)-1-(1-phenyl-ethyl)-piperidine-2-
carboxylic Acid Methyl Ester (87). Into a solution of 86 (0.11 g,
0.37 mmol) in dioxane-H2O (3/1, 3.5 mL) were added 2,6-lutidine
(87 µL, 0.74 mmol), osmium tetroxide (2.5% in tert-butyl alcohol,
96 µL), and sodium metaperiodate (0.3 g, 1.36 mmol). The mixture
was stirred at room temperature for 3 h; then water (5 mL) and
CH2Cl2 (10 mL) were added. The aqueous phase was extracted
with CH2Cl2 (3 × 10 mL). The combined organic layers were
washed with brine, dried over Na2SO4, and concentrated. Flash
chromatography (hexane/AcOEt, 5/1) of the residue gave 87 (68
mg, 61%): [R]D -32.1 (c 1.4, CHCl3); 1H NMR (CDCl3, 400 MHz)
δ 9.7 (s, 1H), 7.33-7.24 (m, 5H), 3.65 (q, 1H, J ) 6.6 Hz), 3.63
(s, 3H), 3.40 (d, 1H, J ) 5.0 Hz), 3.10 (m, 1H), 2.91 (m, 1H), 2.42
(m, 2H), 1.78 (m, 2H), 1.53 (m, 4H), 1.33 (d, 3H, J ) 6.6 Hz));
13C NMR (CDCl3, 100 MHz) δ 201.8, 200.7, 172.7, 172.6, 144.8,
144.3, 127.9, 127.8, 126.8, 126.7, 126.6, 126.5, 62.3, 62.1, 61.7,
61.4, 50.2, 50.0, 46.7, 42.0, 41.2, 38.1, 32.7, 25.6, 25.3, 25.2, 25.0,
24.9, 24.7, 20.6; MS (ESI) m/z 304 (M + H+); HRMS calcd for
C18H25NO3 (M + H+) 304.1907, found 304.1918.
(2R,3S)-3-(3-Oxo-propyl)-piperidine-1,2-dicarboxylic Acid
1-tert-Butyl Ester 2-Methyl Ester (88). Into a flask were added
87 (0.34 g, 1.12 mmol), methanol (40 mL), Boc2O (0.5 g, 2.3
mmol), and 10% Pd/C (0.12 g). The mixture was stirred for 16 h
under an atmosphere of H2 (balloon), then filtered through a pad
of Celite. The filtrate was concentrated to dryness under reduced
pressure, and the residue was purified by flash chromatography
(hexane/AcOEt 2/1) to give 88 (0.18 g, 54%): [R]D -10.2 (c 1.0,
CHCl3); 1H NMR (CDCl3, 400 MHz) δ 9.74 (s, 1H), 4.86, 4.66 (s,
1H), 3.90 (m, 1H), 3.66 (s, 3H), 3.16 (m, 1H), 2.49 (m, 2H), 1.80-
1.60 (m, 5H), 1.44 (s, 9H), 1.30 (m, 2H); 13C NMR (CDCl3, 100
MHz) δ 202.2, 200.9, 171.8, 156.1, 155.5, 80.6, 58.1, 56.5, 52.0,
51.9, 41.9, 28.7, 26.7, 26.2, 25.5, 25.0; MS (ESI) m/z 300 (M +
H+).
cis-3-[3-(tert-Butyl-dimethyl-silanyloxy)-propyl]-piperidine-
1,4-dicarboxylic Acid 1-tert-Butyl Ester 4-Ethyl Ester (89). To
a suspension of Mg (0.45 g, 18.5 mmol) in THF (20 mL) was added
dropwise 3-tert-butyldimethylsilanyloxypropyl bromide (3.0 mL,
13 mmol). The mixture was stirred at room temperature for 2 h to
form the Grignard reagent. Into another 100 mL flask were added
CuI (1.2 g, 6.5 mmol) and THF (10 mL). The stirring solution was
cooled to -78 °C, and the previously prepared Grignard reagent
was added dropwise through a cannula. The mixture was stirred at
-78 °C for 1 h; then a solution of 64 (0.45 g, 1.74 mmol),
trimethylsilyl chloride (TMSCl; 1.63 mL, 13.5 mmol), and hex-
amethylphosphoramide (HMPA) (2.25 mL, 13.5 mmol) in THF (7
mL) was added slowly through a syringe pump over a period of 2
h. The mixture was stirred at -78 °C for another 3 h and then
gradually warmed to -20 °C for 2 h. The reaction was quenched
by adding saturated NH4Cl and NH4OH (4/1, 30 mL). The mixture
was extracted with Et2O (3 × 50 mL), and the combined organic
layers were washed with brine (3 × 50 mL), dried over Na2SO4,
and concentrated under reduced pressure. Flash chromatography
(hexane/AcOEt 5/1) of the residue gave 89 (0.4 g, 68%), and 64
(0.14 g) was also recovered: 1H NMR (CDCl3, 400 MHz) δ 4.15
(m, 2H), 3.85 (m, 2H), 3.60 (m, 2H), 3.10 (m, 2H), 2.64 (m, 1H),
1.97 (m, 1H), 1.80 (m, 1H), 1.66 (m, 2H), 1.51 (m, 1H), 1.46 (s,
9H), 1.32 (m, 1H), 1.27 (t, 3H, J ) 7.1 Hz), 1.12 (m, 1H), 0.89 (s,
9H), 0.04 (s, 6H); 13C NMR (CDCl3, 100 MHz) δ 174.2, 155.4,
80.0, 63.6, 60.6, 46.6, 44.7, 42.7, 37.1, 31.2, 28.8, 26.3, 24.3, 18.7,
14.7, -4.7; MS (ESI) m/z 430 (M + H+).
cis-3-(3-Hydroxy-propyl)-piperidine-1,4-dicarboxylic Acid
1-tert-Butyl Ester 4-Ethyl Ester (90). Into a solution of 89 (100
mg, 0.23 mmol) in THF (2.3 mL) was added TBAF (1 N in THF,
0.4 mL) at 0 °C. The mixture was stirred at 0 °C to room
temperature for 3 h, then saturated NH4Cl (2 mL) was added, and
the mixture was extracted with AcOEt (3 × 20 mL). The combined
organic layers were washed with brine, dried over Na2SO4, and
concentrated. Flash chromatography (hexane/AcOEt 1/1) of the
residue gave racemic 90 (65 mg, 90%): 1H NMR (CDCl3, 400
MHz) δ 4.17 (m, 2H), 3.97 (m, 2H), 3.66 (m, 2H), 3.04 (dd, 1H,
J ) 13.3, 2.4 Hz), 2.96 (ddd, 1H, J ) 13.6, 10.0, 4.0 Hz), 2.65 (dt,
1H, J ) 9.9, 4.5 Hz), 2.02 (m, 1H), 1.87-1.67 (m, 4H), 1.58 (m,
1H), 1.47 (s, 9H), 1.40 (m, 1H), 1.28 (t, 3H, J ) 7.1 Hz), 1.20 (m,
1H); 13C NMR (CDCl3, 100 MHz) δ 174.2, 155.6, 80.1, 62.9, 60.8,
46.3, 45.2, 43.1, 36.8, 31.1, 28.8, 24.3, 23.4, 14.7; MS (ESI) m/z
315 (M + H+); HRMS (FAB) calcd for C16H29NO5 (M + H+)
315.2046, found 315.2047.
cis-3-(3-Oxo-propyl)-piperidine-1,4-dicarboxylic Acid 1-tert-
Butyl Ester 4-Ethyl Ester (91). Into a solution of 90 (54 mg, 0.17
mmol) in CH2Cl2 (2 mL) was added Dess-Martin periodinane (0.1
g, 0.24 mmol) portionwise at 10 °C. The mixture was stirred at
room temperature overnight, then saturated NaHCO3 (1.5 mL) and
Na2S2O3 (2 mL) were added, and the mixture was extracted with
CH2Cl2 (3 × 10 mL). The combined organic layers were washed
with brine, dried over Na2SO4, and concentrated. Flash chroma-
tography (hexane/AcOEt 2/1) of the residue gave racemic 91 (42
mg, 80%): 1H NMR (CDCl3, 400 MHz) δ 9.73 (s, 1H), 4.12 (q,
2H, J ) 7.1 Hz), 4.0 (b, 1H), 3.83 (dd, 1H, J ) 13.5, 4.3 Hz), 3.01
(dd, 1H, J ) 13.6, 2.7 Hz), 2.85 (b, 1H), 2.61 (dt, 1H, J ) 10.0,
4.4 Hz), 2.48 (m, 2H), 1.96 (m, 1H), 1.83-1.59 (m, 3H), 1.46 (m,
1H), 1.43 (s, 9H), 1.23 (t, 3H, J ) 7.1 Hz), 1.20 (m, 1H); 13C
NMR (CDCl3, 100 MHz) δ 202.1, 173.8, 155.4, 80.1, 60.9, 46.3,
45.3, 44.7, 42.3, 41.5, 36.4, 32.2, 28.8, 24.1, 19.9, 14.6; MS (ESI)
m/z 314 (M + H+).
cis-3-[4-(2-Trimethylsilanyl-ethoxycarbonyl)-but-3-enyl]-pi-
peridine-1,4-dicarboxylic Acid 1-tert-Butyl Ester 4-Ethyl Ester
(92). Into a solution of 91 (110 mg, 0.35 mmol) in CH2Cl2 (5 mL)
was added Ph3PdCHCO2TMSE (0.28 g, 0.7 mmol). The mixture
was stirred at room temperature overnight and then concentrated.
Flash chromatography (hexane/AcOEt 5/1) of the residue gave
racemic 92 (120 mg, 75%): 1H NMR (CDCl3, 400 MHz) δ 6.9
(dt, 1H, J ) 15.6, 7.2 Hz), 5.82 (d, 1H, J ) 15.6 Hz), 4.22 (t, 2H,
J ) 8.4 Hz), 4.13 (q, 2H, J ) 7.0 Hz), 4.09 (m, 1H), 3.89 (dd, 1H,
J ) 13.6, 4.1 Hz), 3.04 (m, 1H), 2.63 (dt, 1H, J ) 9.7, 4.6 Hz),
2.36 (m, 1H), 2.21 (m, 1H), 1.99 (m, 1H), 1.80-1.59 (m, 3H),
1.49 (m, 1H), 1.45 (s, 9H), 1.27 (t, 3H, J ) 7.0 Hz), 1.10 (t, 2H,
J ) 8.4 Hz), 0.05 (s, 9H); 13C NMR (CDCl3, 100 MHz) δ 173.9,
167.1, 156.2, 144.4, 122.4, 80.0, 62.9, 60.9, 45.0, 44.4, 36.4, 30.2,
28.8, 26.2, 25.4, 19.7, 14.7, -1.3; MS (ESI) m/z 456 (M + H+);
HRMS calcd for C23H41NO6Si (M + H+) 456.2776, found
456.2777.
cis-3-(4-Carboxy-but-3-enyl)-piperidine-1,4-dicarboxylic Acid
1-tert-Butyl Ester 4-Ethyl Ester (93). Into a solution of 92 (150
mg, 0.33 mmol) in THF (2.6 mL) were added TBAF (1 N in THF,
0.66 mL) and 4 Å molecular sieves at 0 °C. The mixture was stirred
at 0 °C to room temperature for 3 h, then 10% citric acid was added
to pH 3.0, and the mixture was extracted with AcOEt (3 × 20 mL).
The combined organic layers were sequentially washed with 10%
citric acid, then with brine, dried over Na2SO4, and concentrated.
Flash chromatography (hexane/AcOEt 1/1 and 1/2) of the residue
gave racemic 93 (72 mg, 63%): 1H NMR (CDCl3, 400 MHz) δ
7.03 (dt, 1H, J ) 15.5, 6.8 Hz), 5.84 (d, 1H, J ) 15.6 Hz), 4.15
(m, 2H), 4.04 (m, 1H), 3.90 (dd, 1H, J ) 13.6, 4.3 Hz), 3.02 (d,
1H, J ) 11.7 Hz), 2.90 (b, 1H), 2.63 (m, 1H), 2.39 (m, 1H), 2.24
(m, 1H), 2.03 (m, 1H), 1.79-1.61 (m, 2H), 1.54 (m, 1H), 1.46 (s,
9H), 1.30 (m, 2H), 1.26 (t, 3H, J ) 7.0 Hz); 13C NMR (CDCl3,

Macroheterocyclic Peptidomimetic BACE Inhibitors
Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15 4565
100 MHz) δ 173.9, 171.8, 155.2, 151.2, 121.6, 80.2, 60.9, 46.3,
44.9, 42.5, 36.3, 30.4, 28.8, 25.4, 23.8, 14.6; MS (ESI) m/z 356
(M + H+).
17.6, 17.4, 17.2, 13.2; MS (FAB) m/z 704 (M + H+); HRMS calcd
for C37H60N4O7S (M + H+) 705.4256, found 705.4259.
(4R,7R,10S,18R,1′R,3′S)-10-(3-Butylcarbamoyl-1-hydroxy-bu-
tyl)-7-methyl-5,8-dioxo-3,4,4a,5,6,7,8,9,10,11,13,16,17,17a-tet-
radecahydro-1H-12-thia-2,6,9-triaza-benzocyclopentadecene-2-
carboxylic Acid tert-Butyl Ester (98). Na was added portionwise
to 96 (47 mg, 0.68 mmol) in liquid ammonia (80 mL) at -78 °C
until a permanent blue coloration persisted. After the mixture was
stirred for another 15 min, the color was then discharged by addition
of the minimum quantity of solid NH4Cl. Liquid ammonia was
evaporated under a stream of argon. The residue was dissolved in
AcOEt (40 mL), washed sequentially with 1 N HCl (3 mL) and
then with brine, dried over Na2SO4, and concentrated to give a thiol
(42 mg). To a solution of this thiol (42 mg, 0.068 mmol) in CH2-
Cl2 (12 mL) were added 1,1′-(azodicarbonyl)dipiperidine (ADDP)
(33.6 mg, 0.14 mmol) and imidazole (9.0 mg, 0.14 mmol).
Trimethylphosphine (1 M in toluene, 0.14 mL) was then added
dropwise. The mixture was stirred at room temperature for 20 h
and evaporated. Flash chromatography (10% MeOH in AcOEt) of
the residue gave product 98 (12 mg, 30%): [R]D -9.1 (c 0.35,
cis-3-(5-Hydroxy-pent-3-enyl)-piperidine-1,4-dicarboxylic Acid
1-tert-Butyl Ester 4-Ethyl Ester (94). Into a solution of 93 (40
mg, 0.11 mmol) and triethylamine (0.019 mL, 0.14 mmol) in THF
(3.2 mL) was added ethyl chloroformate (0.13 mL, 0.14 mmol) at
-5 °C. The mixture was stirred for 20 min, and then sodium
borohydride (17.2 mg, 0.44 mmol) and methanol (0.32 mL) were
added consecutively. The mixture was stirred for 30 min at -5
°C, and then saturated NH4Cl was added to quench the reaction.
The mixture was extracted with Et2O (3 × 10 mL), and the
combined organic layers were washed with brine, dried over Na2-
SO4, and concentrated. Flash chromatography (hexane/AcOEt 1/1)
of the residue gave racemic 94 (24 mg, 60%): 1H NMR (CDCl3,
400 MHz) δ 5.62 (m, 2H), 4.28 (m, 1H), 4.15 (m, 4H), 3.76 (m,
2H), 3.05-2.82 (m, 2H), 2.62 (m, 1H), 2.26 (b, 1H), 2.0 (m, 2H),
1.82-1.70 (m, 3H), 1.46 (s, 9H), 1.26 (t, 3H, J ) 7.0 Hz), 1.21
(m, 1H); 13C NMR (CDCl3, 100 MHz) δ 174.2, 155.4, 132.9, 130.2,
80.0, 77.6, 64.1, 60.9, 44.9, 42.6, 36.4, 30.5, 30.1, 28.8, 14.7; MS
(FAB) m/z 342 (M + H+).
1
MeOH); H NMR (MeOD, 400 MHz) δ 7.81 (b, 1H), 5.58 (m,
1H), 5.28 (m, 1H), 4.46 (dt, 1H, J ) 6.9, 4.0 Hz), 4.10 (m, 2H),
3.86(d, 1H, J ) 6.8 Hz), 3.77 (t, 1H, J ) 9.6 Hz), 3.19 (m, 3H),
2.98 (m, 2H), 2.68 (m, 3H), 2.56 (m, 1H), 2.33 (m, 1H), 2.17 (m,
1H), 1.99 (m, 2H), 1.75 (m, 2H), 1.52 (m, 2H), 1.46 (s, 9H), 1.39
(m, 3H), 1.33 (d, 1H, J ) 7.0 Hz), 1.14 (d, 3H, J ) 6.9 Hz), 0.95
(t, 3H, J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz) δ 178.0, 174.1,
172.7, 155.6, 135.5, 125.5, 80.0, 69.4, 53.7, 49.8, 46.1, 39.0, 38.9,
37.8, 36.8, 32.1, 31.7, 29.7, 29.5, 27.7, 25.6, 20.1, 17.7, 17.0, 13.2;
MS (ESI) m/z 597 (M + H+), 497 (M-Boc)+. HRMS calcd for
C30H52N4O6S (M + H+) 597.3680, found 597.3691; LC/MS
retention time [A] 6.16 min, [B] 8.15 min.
(2S,4R,4′R,7′R,10′S,18′R)-N-Butyl-4-hydroxy-2-methyl-4-(7-
methyl-5,8-dioxo-1,2,3,4,4a,5,6,7,8,9,10,11,13,16,17,17a-hexa-
decahydro-12-thia-2,6,9-triaza-benzocyclopentadecen-10-yl)-
butyramide (99). Into a solution of 98 (7 mg, 0.012 mmol) in
CH2Cl2 (3 mL) was added TFA (0.5 mL), and the mixture was
stirred at room temperature for 30 min. The solvent and excess
TFA were removed under reduced pressure. The residue was
dissolved in AcOEt (20 mL), washed sequentially with saturated
NaHCO3 and with brine, dried over Na2SO4, and concentrated to
give 99 (6 mg, quant): [R]D -3.3 (c 0.3, MeOH); 1H NMR (MeOD,
400 MHz) δ 5.58 (m, 1H), 5.32 (m, 1H), 4.64 (b, 1h), 4.47 (q, 1H,
J ) 7.1 Hz), 4.36 (q, 1H, J ) 7.1 Hz), 3.81 (m, 2H), 3.19 (m, 3H),
2.98 (m, 3H), 2.75 (m, 2H), 2.61 (m, 1H), 2.40 (dd, 1H, J ) 14.2,
4.0 Hz), 2.15 (m, 1H), 2.03 (m, 2H), 1.68 (m, 3H), 1.49 (m, 3H),
1.40-1.24 (m, 8H), 1.14 (d, 3H, J ) 7.0 Hz), 0.96 (t, 3H, J ) 7.3
Hz); 13C NMR (MeOD, 100 MHz) δ 178.0, 175.2, 173.7, 134.8,
125.9, 67.8, 53.4, 45.8, 42.6, 42.2, 39.1, 38.6, 37.7, 35.2, 32.4, 31.7,
29.7, 28.9, 26.3, 22.4, 20.1, 17.7, 17.1, 13.1; MS (ESI) m/z 497
(M + H+); HRMS calcd for C25H44N4O4S (M + H+) 497.3156,
found 497.3157; LC/MS retention time [A] 16.95 min, [B] 21.50
min.
(4S,7R,10S,18S,1′R,3′S)-10-(3-Butylcarbamoyl-1-hydroxy-bu-
tyl)-7-methyl-5,8-dioxo-3,4,4a,5,6,7,8,9,10,11,13,16,17,17a-tet-
radecahydro-1H-12-thia-2,6,9-triaza-benzocyclopentadecene-2-
carboxylic Acid tert-Butyl Ester (100). Compound 100 (12 mg,
46%) was prepared from 97 (27 mg, 0.038 mmol) according to the
procedure for the preparation of 98: [R]D +21 (c 0.3, MeOH); 1H
NMR (MeOD, 400 MHz) δ 5.56 (m, 1H), 5.27 (m, 1H), 4.33 (dt,
1H, J ) 7.3, 6.9 Hz), 4.13 (m, 2H), 3.84 (m, 1H), 3.74 (m, 1H),
3.40 (m, 1H), 3.17 (td, 1H, J ) 6.9, 2.8 Hz), 3.10 (d, 1H, J ) 7.0
Hz), 2.98 (m, 2H), 2.69 (m, 2H), 2.50 (m, 2H), 2.23 (m, 1H), 2.16
(m, 1H), 1.89 (m, 2H), 1.62 (m, 3H), 1.56 (m, 3H), 1.46 (s, 9H),
1.37 (m, 3H), 1.32 (d, 1H, J ) 7.0 Hz), 1.142 (d, 3H, J ) 6.9 Hz),
0.95 (t, 3H, J ) 7.2 Hz); 13C NMR (MeOD, 100 MHz) δ 177.9,
176.0, 174.2, 155.8, 135.3, 121.6, 80.1, 67.4, 53.8, 50.3, 45.0, 39.0,
38.8, 37.8, 36.6, 33.1, 31.7, 29.8, 27.7, 25.7, 24.5, 20.1, 17.7, 15.5,
13.2; MS (ESI) m/z 619 (M + Na+), 497 (M-Boc)+; HRMS calcd
for C30H52N4O6S (M + H+) 597.3680, found 597.3678; LC/MS
retention time [A] 22.11 min, [B] 30.18 min.
cis-3-(5-Hydroxy-pent-3-enyl)-piperidine-1,4-dicarboxylic Acid
1-tert-Butyl Ester (95). Into a solution of 94 (25 mg, 0.073 mmol)
in THF (0.4 mL) was added 1 N LiOH (0.3 mL, 0.3 mmol) at
room temperature. The mixture was stirred overnight, then 10%
citric acid was added to pH 2, and the mixture was extracted with
AcOEt (3 × 20 mL). The combined organic layers were washed
with brine, dried over Na2SO4, and concentrated to give racemic
95 (22 mg, 96%): 1H NMR (MeOD, 400 MHz) δ 5.65 (m, 2H),
4.01 (m, 4H), 3.05 (dd, 1H, J ) 13.6, 2.7 Hz), 2.88 (m, 1H), 2.68
(dt, 1H, J ) 10.2, 4.4 Hz), 2.17 (m, 1H), 2.05 (m, 2H), 1.72 (m,
2H), 1.48 (s, 9H), 1.42 (m, 2H); 13C NMR (CDCl3, 100 MHz) δ
176.7, 155.7, 131.5, 130.0, 80.1, 62.6, 46.2, 44.8, 43.6, 42.4, 36.3,
30.2, 27.7, 26.1; MS (ESI) m/z 336 (M + Na+), 314 (M + H+).
(3R,4R,1′R,1′′S,2′′R,4′′S)-4-[1-(1-Benzylsulfanylmethyl-4-bu-
tylcarbamoyl-2-hydroxy-pentylcarbamoyl)-ethyl carbamoyl]-3-
(5-hydroxy-pent-3-enyl)-piperidine-1-carboxylic Acid tert-Butyl
Ester (96) and (3S,4S,1′R,1′′S,2′′R,4′′S)-4-[1-(1-Benzylsulfanyl-
methyl-4-butylcarbamoyl-2-hydroxy-pentylcarbamoyl)-ethyl car-
bamoyl]-3-(5-hydroxy-pent-3-enyl)-piperidine-1-carboxylic Acid
tert-Butyl Ester (97). Into a solution of 95 (25 mg, 0.073 mmol)
and 5-(2-amino-propionylamino)-6-benzylsulfanyl-4-hydroxy-2-
methyl-hexanoic acid butylamide (prepared separately, 36 mg, 0.088
mmol) in CH2Cl2 (3 mL) were added PyBOP (57 mg, 0.11 mmol)
and DIEA (30 µL, 0.16 mmol) at 0 °C. The mixture was stirred at
0 °C to room temperature for 4 h, and then 10% citric acid (1 mL)
was added. The mixture was extracted with AcOEt (3 × 20 mL).
The combined organic layers were sequentially washed with
saturated NaHCO3 and with brine, then dried over Na2SO4, and
concentrated to give a mixture of two diastereoisomers, 96 (18 mg,
35%) and 97 (18 mg 35%), which were separated by flash
chromatography (4% MeOH in AcOEt). For 96: [R]D -38 (c 0.3,
MeOH); 1H NMR (MeOD, 400 MHz) δ 7.34-7.20 (m, 5H), 5.62
(m, 2H), 4.39 (m, 1H), 4.01-3.94 (m, 5H), 3.76 (m, 1H), 3.74 (s,
2H), 3.16 (m, 3H), 2.61 (m, 2H), 2.51 (m, 2H), 2.22 (m, 1H), 2.06
(m, 1H), 1.92 (m, 1H), 1.84 (m, 1H), 1.62 (m, 2H), 1.51 (m, 2H),
1.46 (s, 9H), 1.35 (m, 7H), 1.11 (d, 3H, J ) 6.9 Hz), 0.93 (t, 3H,
J ) 7.3 Hz); 13C NMR (MeOD, 100 MHz) δ 177.9, 175.2, 174.1,
155.7, 138.8, 129.9, 129.2, 128.5, 126.9, 80.0, 68.6, 62.7, 62.6,
52.8, 49.5, 49.3, 39.1, 38.4, 37.6, 37.1, 35.7, 35.6, 32.6, 31.7, 30.1,
27.7, 20.1, 17.7, 17.4, 17.2, 13.2; MS (FAB) m/z 704 (M + H+);
HRMS calcd for C37H60N4O7S (M + H+) 705.4256, found
1
705.4265. For 97: [R]D -47 (c 0.6, MeOH); H NMR (MeOD,
400 MHz) δ 7.35-7.25 (m, 5H), 5.62 (m, 2H), 4.40 (m, 1H), 4.01-
3.94 (m, 4H), 3.80 (m, 1H), 3.75 (s, 2H), 3.19 (m, 3H), 2.89 (m,
1H), 2.64 (m, 2H), 2.53 (m, 2H), 2.20 (m, 1H), 2.05 (m, 1H), 1.92
(m, 1H), 1.82 (m, 1H), 1.61 (m, 2H), 1.52 (m, 2H), 1.47 (s, 9H),
1.39 (m, 8H), 1.12 (d, 3H, J ) 6.9 Hz), 0.95 (t, 3H, J ) 7.3 Hz);
13C NMR (MeOD, 100 MHz) δ 177.9, 175.0, 174.3, 155.7, 138.8,
130.1, 129.2, 128.4, 126.9, 80.0, 68.6, 62.6, 52.8, 52.6, 49.6, 49.3,
39.1, 38.3, 37.6, 37.1, 35.7, 32.7, 32.6, 31.7, 30.0, 27.7, 20.1, 17.7,

4566 Journal of Medicinal Chemistry, 2006, Vol. 49, No. 15
Hanessian et al.
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(2S,4R,4′S,7′R,10′S,18′S)-N-Butyl-4-hydroxy-2-methyl-4-(7-
methyl-5,8-dioxo-1,2,3,4,4a,5,6,7,8,9,10,11,13,16,17,17a-hexa-
decahydro-12-thia-2,6,9-triaza-benzocyclopentadecen-10-yl)-
butyramide (101). Compound 101 (6 mg, quant) was prepared from
100 (7 mg, 0.012 mmol) according to the procedure described for
the preparation of 99: [R]D +34.4 (c 0.25, MeOH); 1H NMR
(MeOD, 400 MHz) δ 5.55 (m, 1H), 5.28 (m, 1H), 4.65 (b, 1H),
4.35 (q, 1H, J ) 6.6 Hz), 3.84 (m, 1H), 3.77 (m, 1H), 3.42 (m,
1H), 3.19 (q, 1H, J ) 7.0 Hz), 3.13 (t, 1H, J ) 7.8 Hz), 3.0 (m,
2H), 2.85 (m, 1H), 2.71 (m, 1H), 2.62 (m, 1H), 2.51 (dd, 1H, J )
13.0, 3.3 Hz), 2.25 (m, 2H), 2.05 (m, 2H), 1.85 (m, 2H), 1.63 (m,
4H), 1.51 (m, 2H), 1.47-1.28 (m, 6H), 1.14 (d, 3H, J ) 6.9 Hz),
0.96 (t, 3H, J ) 7.2 Hz); 13C NMR (MeOD, 100 MHz) δ 178.0,
175.1, 174.2, 134.3, 125.8, 67.0, 54.0, 50.4, 46.2, 44.9, 43.8, 39.0,
38.8, 37.8, 36.6, 33.1, 31.7, 29.8, 29.2, 25.7, 20.1, 17.8, 15.6, 13.2;
MS (ESI) m/z 497 (M + H+); HRMS calcd for C25H44N4O4S (M
+ H+) 497.3156, found 497.3154; LC/MS retention time [A] 15.88
min, [B] 21.18 min.
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Acknowledgment. We thank NSERC (Canada) for financial
assistance, Dr. Michel Simard for X-ray analysis of compound
59, Dalbir Sekon for LC/MS analyses, and Guillaume Charron
for proofreading. S.H. thanks Novartis Pharma AG, Basel/
Switzerland, for generous financial support. We also thank Rene´
Hemmig, Sylvie Lehmann, and Sebastien Rieffel for technical
support. X-ray data collection for the enzyme complexes was
performed at the Swiss Light Source, Paul Scherrer Institut,
Villigen, Switzerland. We are grateful to the machine and
beamline groups whose outstanding efforts have made these
experiments possible.
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Supporting Information Available: Experimental details for
enzyme inhibition measurements, modeling of compounds in
BACE, and crystallization, as well as crystal structure data. This
material is available free of charge via the Internet at http://
pubs.acs.org. The X-ray structures of the BACE complexes with
compounds 42 and 52 have been deposited with the Protein Data
Bank (PDB identifier 2F3E and 2F3F, respectively).
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