Design, synthesis, biological evaluation and X-ray structural studies of HIV-1 protease inhibitors containing substituted fused-tetrahydropyranyl tetrahydrofuran as P2-ligands

Article abstract of DOI:10.1039/c5ob01930c

Design, synthesis, biological and X-ray crystallographic studies of a series of potent HIV-1 protease inhibitors are described. Various polar functionalities have been incorporated on the tetrahydropyranyl-tetrahydrofuran-derived P2 ligand to interact with the backbone atoms in the S2-subsite. The majority of the inhibitors showed very potent enzyme inhibitory and antiviral activity. Two high-resolution X-ray structures of 30b- and 30j-bound HIV-1 protease provide insight into ligand-binding site interactions. In particular, the polar functionalities on the P2-ligand appear to form unique hydrogen bonds with Gly48 amide NH and amide carbonyl groups in the flap region.

Full text of DOI:10.1039/c5ob01930c

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Biomolecular Chemistry
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Design, synthesis, biological evaluation and X-ray
structural studies of HIV-1 protease inhibitors
containing substituted fused-tetrahydropyranyl
tetrahydrofuran as P2-ligands†
Cite this: DOI: 10.1039/c5ob01930c
a
a
a
a
Arun K. Ghosh,* Cuthbert D. Martyr, Luke A. Kassekert, Prasanth R. Nyalapatla,
a
b
b
b
Melinda Steffey, Johnson Agniswamy, Yuan-Fang Wang, Irene T. Weber,
c
c,d
Masayuki Amano and Hiroaki Mitsuya
Design, synthesis, biological and X-ray crystallographic studies of a series of potent HIV-1 protease inhibi-
tors are described. Various polar functionalities have been incorporated on the tetrahydropyranyl-tetra-
hydrofuran-derived P2 ligand to interact with the backbone atoms in the S2-subsite. The majority of the
inhibitors showed very potent enzyme inhibitory and antiviral activity. Two high-resolution X-ray
structures of 30b- and 30j-bound HIV-1 protease provide insight into ligand-binding site interactions. In
particular, the polar functionalities on the P2-ligand appear to form unique hydrogen bonds with Gly48
amide NH and amide carbonyl groups in the flap region.
Received 16th September 2015,
Accepted 6th October 2015
DOI: 10.1039/c5ob01930c
www.rsc.org/obc
Introduction
The development of human immunodeficiency virus type 1
HIV-1) protease inhibitors (PIs) as part of the current active
antiretroviral therapy has significantly reduced the mortality of
(
1
,2
HIV/AIDS patients. However, one of the major drawbacks of
many approved protease inhibitors is the emergence of drug
resistant HIV-1 strains which may severely limit long-term
3
,4
treatment options.
Therefore, design and development of
protease inhibitors with broad-spectrum activity against multi-
drug-resistant HIV-1 variants are critically important. As part
of our continuing interest to develop novel PIs, we reported a
variety of novel inhibitors that are potent against HIV-1 vari-
5
,6
ants resistant to currently approved PIs. One of these PIs is
darunavir (1, Fig. 1), which contains a structure-based designed
nonpeptidic P2 ligand, 3(R),3a(S),6a(R)-bis-tetrahydrofuranyl
a
Departments of Chemistry and Medicinal Chemistry, Purdue University,
West Lafayette, IN 47907, USA. E-mail: akghosh@purdue.edu; Fax: +1 765 4961612;
Tel: +1 765 4945323
Fig. 1 Structure of PIs 1–4 and 30f,j.
b
Department of Biology, Molecular Basis of Disease, Georgia State University,
Atlanta, Georgia 30303, USA
c
Kumamoto University School of Medicine, Department of Hematology and Infectious
diseases, Kumamoto 860-8556, Japan
urethane (bis-THF), and was approved as a first-line therapy
for the treatment of HIV/AIDS patients.
d
Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National
7–10
Cancer Institute, Bethesda, Maryland 20892, USA
The bis-THF ligand in darunavir is responsible for its
†
Electronic supplementary information (ESI) available: Crystallographic data col-
5,7
superb activity against multidrug resistant HIV-1 strains. In
lection, refinement statistics and NMR spectra of compounds. See DOI: 10.1039/
c5ob01930c
an effort to further optimize the structural feature of bis-THF,
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we have designed a furopyranol or tetrahydropyranyl tetra-
11,12
hydrofuran (Tp-THF) ligand.
The X-ray structure of inhibitors
1
and 2 with HIV-1 protease revealed that both ring oxygens
are involved in strong hydrogen bonding interactions with the
backbone NHs of Asp29 and Asp30 in the S2 subsite. Also, the
bicyclic ring system fills in the hydrophobic pocket in the S2
site. We have recently incorporated substituents on the bis-
THF and Cp-THF rings (inhibitor 3) to effect specific ligand-
binding site interactions in the S2-subsite of HIV-1
1
3–16
protease.
Hohlfeld and co-workers have also reported
potent HIV-1 protease inhibitors incorporating substituted bis-
1
7,18
THF ligands.
To further optimize ligand-binding site inter-
actions, we speculated that a larger tetrahydropyranyl ring in
place of the tri-substituted THF ring may improve hydrogen
bonding with the active site aspartate backbone NHs due to an
increase in the dihedral angle of the bicyclic acetal bearing the
tetrahydropyranyl-tetrahydrofuran ring system. Furthermore, a
larger THP-ring in the fused THP-THF (Tp-THF) ligand may
enhance van der Waals interactions. Tp-THF ligand-derived
inhibitor 4 exhibited high enzyme affinity and antiviral activity.
Also, inhibitor 4 has been shown to retain high potency
against a variety of multi-drug resistant clinical HIV-1 strains
with EC50 values in low nanomolar range. In an effort to
further improve backbone ligand-binding site interactions,
based upon the X-ray structure of 4-bound HIV-1 protease, we
have incorporated various polar substituents at the C5-position
Scheme 1 Reagents and conditions: (a) Dibal-H, CH
b) MeOH, Ph PvCHCO Et, 0 °C, 70%; (c) Dibal-H, CH
of Tp-THF ligand. We speculated that a stereochemically (d) t-butyl bromoacetate, CsOH·H O, TBAI, CH CN, 12 h, 95% 2 steps;
2
Cl
2
, −78 °C, 1 h;
(
3
2
2
Cl , −78 °C;
2
2
3
(
(
(
e) LiHMDS, THF, −65 °C–20 °C, 2 h, 77% overall, major/minor (8.5 : 1);
f) MsCl, Et N, THF, 0 °C, 1 h; (g) LAH, THF, 23 °C, 24 h, 70% 2 steps;
h) O , DMS, −78 °C, then p-TsOH, 23 °C, 18 h, 70%.
defined hydroxyl group, alkoxy group or amine derivative
could form a hydrogen bond with the backbone atoms of
Gly48 located in the flap region of HIV-1 protease. Also, the
corresponding alkyl chain may enhance additional van der
Waals interactions in the active site. Herein we report our
3
3
1
6,20
studies on the design, synthesis, biological evaluation and (diastereomeric ratio 8.5 : 1).
The absolute stereochemical
X-ray structural studies of C5-substituted tetrahydropyranyl- configuration of the major isomer 9 was determined through
tetrahydrofuran ligands. A number of inhibitors exhibited very the use of 2D COSY and 1D NOE after conversion to the
high enzyme inhibitory and antiviral activity. For the synthesis subsequent ligand derivatives.
of the tetrahydropyranyl-tetrahydrofuran ring system P2-
The stereochemical outcome of the [2,3]-sigmatropic
ligands in this study, we developed a highly diastereoselective rearrangement can be rationalized based upon the transition
2
1,22
tetrahydropyranyl-tetrahydrofuran ring system using a [2,3]- state model 8 as described in the literature.
The observed
sigmatropic rearrangement as the key reaction.
selectivity is somewhat lower as compared to the isopropyl-
idene derivative. This is possibly due to the greater flexibility
of the 6-membered dioxane ring in substrate 7. Mesylation of
compound 9 followed by lithium aluminum hydride reduction
gave alcohol 11 in 70% yield over 2 steps. Ozonolysis and sub-
Results and discussion
Synthesis of the fused tetrahydropyranyl-tetrahydrofuran sequent acid-catalyzed cyclization resulted in the desired
ligand is shown in Scheme 1. Methyl ester 5 is obtained in Tp-THF ligand 12 in 70% yield. The route provided Tp-THF
four steps from L-malic acid as described by Solladié and co- ligand 12 in 25% overall yield from 5. This ligand was con-
1
9
14,23
workers. Dibal-H reduction of 5 provided the corresponding verted to the desired inhibitor as described previously.
aldehyde. Wittig olefination of the resulting aldehyde in The sigmatropic rearrangement product 9 is an effective inter-
MeOH at 0 °C afforded α,β-unsaturated ester 6 in 70% yield as mediate for the synthesis of substituted P2-ligands. As shown
a mixture (8 : 1) of cis/trans isomers. Dibal-H reduction of 6 in Scheme 2, the hydroxyl group was converted to methyl
provided the corresponding cis-alcohol. Cesium hydroxide-pro- ether 13 using NaH and methyl iodide in THF. Reduction of
4
moted O-alkylation with t-butyl bromoacetate gave the desired 13 by LiAlH , ozonolytic cleavage of the double bond, and
alkylated product 7 in 95% yield over 2 steps. Sigmatropic subsequent treatment of the resulting aldehyde with p-TsOH
rearrangement of 7 using LiHMDS at −65 °C resulted in a in THF provided the corresponding C3-methoxy substituted
mixture of rearrangement products 9 and 10 in 77% yield ligand 14.
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Scheme 3 Reagents and conditions: (a) LAH, THF, 0 °C–23 °C, 1 h; (b)
TrCl, Et
°C–23 °C, 24 h, 70%; (d) O
4%; (e) Pd/C, H , MeOH, 1 h; (f) PhCHO, NaBH
3
N, CH
2
Cl
2
, 23 °C, 18 h, 92% 2 steps; (c) PPh
, DMS, −78 °C, then p-TsOH, 23 °C, 18 h,
CN, MeOH, then RCHO,
3
, DPPA, DEAD, THF,
0
7
2
3
2
3
4 h, 45–81%.
Scheme 2 Reagents and conditions: (a) NaH, MeI, THF, 0 °C–23 °C,
This double alkylation was carried out in a single pot
9
0%; (e) PPh
LAH; (c) O , DMS; (d), THF, p-TsOH, 30%, 2 steps; (f) K
°C, 1 h, 98%; (g) MeI, NaH, THF, 0 °C–23 °C, or, BnBr, TBAI, NaH, THF,
°C to 23 °C 2 h; (h) LAH, THF, 0 °C, 1 h; (i) O , DMS, then, THF, p-TsOH.
3
, DIAD, p-nitrobenzoic acid, CH
2
Cl
2
, 0 °C, 18 h, 81%; (b)
2
2,25
3
2
CO
3
, MeOH, operation.
0
0
For the synthesis of C3-substituted Tp-THF-derived inhibi-
tors, various selected alcohol derivatives were converted to the
corresponding mixed activated carbonate derivatives 27a–h. As
shown in Scheme 4, optically active ligand alcohols (14, 19–21,
3
Rearrangement product 9 was subjected to Mitsunobu 23–26) were reacted with 4-nitrophenyl chloroformate and pyri-
2
4
inversion with p-nitrobenzoic acid to provide benzoate 15.
dine in CH Cl at 0 °C to 23 °C for 12 h, furnishing mixed
2 2
26
Selective deprotection of the p-nitrobenzoate in the presence carbonates 27a–h in 24–90% yields. The synthesis of inhibitors
of the t-butyl ester was accomplished in K CO and MeOH at with hydroxyethylsulfonamide isosteres with p-methoxysulfon-
2
3
0
°C over 1 h. Alkylation of the resulting alcohol using NaH amide and p-aminosulfonamide as the P2′-ligand is shown in
and the respective alkyl halide provided the corresponding Scheme 5. Treatment of amines 28 and 29 with mixed acti-
alkylated product in high yield (88–96%). Ozonolysis of the O- vated carbonates 27a–e in CH CN in the presence of diiso-
3
alkylated products 16–18, followed by acid-catalyzed cycliza- propylethylamine (DIPEA) provided inhibitors 30a–e,g. For the
tion, gave various C3 O-alkylated Tp-THF ligands 19–21 in synthesis of inhibitor 30f, inhibitor 30e was subjected to cata-
6
0–70% yield.
lytic hydrogenation using Pearlman’s Catalyst in MeOH at
The synthesis of various C3-amine derivatives was accom- 60 psi hydrogen pressure for 12 h. This resulted in inhibitor
plished utilizing hydroxy ester 9. As shown in Scheme 3, 30f in 38% yield over two steps. Similarly, hydrogenation of
reduction of 9 with LAH provided the corresponding diol. azide 30g over 10% Pd-C in ethyl acetate under a hydrogen-
Protection of the primary alcohol with trityl chloride and Et
afforded the trityl derivative 22 in 92% yield over two-steps.
3
N
filled balloon for 1 h provided inhibitor 30h in 85% yield.
For synthesis of inhibitors 30i–l, amines 28 and 29 were
Alcohol 22 was subjected to Mitsunobu azidation using di- reacted with active mixed carbonate 27f–h in the presence of
phenyl phosphorazidate (DPPA), triphenyl phosphine and DIPEA to provide the corresponding urethanes. Catalytic
diethyl azodicarboxylate (DEAD) to provide the corresponding hydrogenation of the resulting urethanes provided inhibitors
azide derivative in 70% yield. Ozonolysis of the resulting olefin 30i–l. For the synthesis of inhibitor 30m, methylamine deriva-
followed by treatment with p-TsOH in CH
2
Cl
2
afforded bicyclic tive 30i was subjected to reductive amination using NaBH
3
CN
to
azide derivative 23 in 74% yield in two-steps. Catalytic hydro- in MeOH in the presence of paraformaldehyde in CH
genation of 23 with 10% Pd/C under a hydrogen-filled balloon provide 30m in 67% yield.
Cl
2
2
provided the corresponding amine in near quantitative yield.
As stated earlier, our main objective is to investigate the
The resulting amine was converted to various benzyl deriva- effect of additional inhibitor–HIV-1 protease interactions in
tives as follows: reductive amination with benzyldehyde in the the S2 subsite. In particular, we planned to target the Gly48
presence of NaBH
3
CN in MeOH affording the corresponding backbone atoms in the flap region of HIV-1 protease. We first
benzylamine, which was then subjected to further reductive investigated the effect of the hydroxyl group and its alkyl
amination with formaldehyde, acetaldehyde or propion- ethers at the C5 position of the Tp-THF ligand. The structure
aldehyde to provide substituted amines 24–26 in 45–81% yield. and activity of these inhibitors are shown in Table 1. Enzyme
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2 2
Scheme 4 Reagents and conditions: (a) pyridine, CH Cl , 0 °C–23 °C,
1
2 h (32–90%).
Scheme 5 Reagents and conditions: (a) DIPEA, CH
30–85%); (b) H , Pd(OH) , MeOH, 60 psi; (c) H , 10% Pd-C, EtOAc; (d)
, Pd(OH) , 5% NH in MeOH; (e) NaBH CN, HCHO, MeOH.
3
CN, 23 °C, 24 h
(
H
2
2
2
2
2
3
3
inhibitory potency was evaluated using an assay developed by
2
7
Toth and Marshall. Inhibitors 30a and 30b were designed to
examine the importance of the R/S configuration of the
C5-methoxy group. As it turned out, compound 30b with a
Another objective of our investigation is to incorporate a
basic amine functionality on the P2-ligand. Particularly, in-
5
-(R)-configuration has shown over 300-fold better enzymatic K
i
compared to compound 30a with a 5-(S)-methoxy group. Anti- corporation of an alkyl amine may serve the purpose of hydrogen
viral activity of selected compounds were evaluated using bonding interactions with Gly48 backbone atoms through the
2
8
protocol described previously. Consistent with potent enzyme amine NH. Also, a suitable alkyl group may fill in the hydro-
inhibitory activity of 30b, it showed an antiviral IC50 value of phobic pocket in the S2-subsite. Towards this goal, we have
0
.2 nM, which is over 85-fold better than the antiviral activity incorporated various amine and substituted amine derivatives
of 30a. Based upon our preliminary model, we presume at the C5-position of the Tp-THF ligand. Based upon previous
that C5-(R)-configuration is optimum for hydrogen bonding observation of the preference for the C5-(R)-configuration, we
interactions with Gly48 backbone atoms. We subsequently have investigated derivatives containing 5-(R)-configuration.
investigated other C5-substituents. Compound 30c with 4-amino- The structures and activity of amine derivatives are shown
sulfonamide as the P2′-ligand showed reduction of potency in Table 2. As can be seen, compounds 30g and 30h with
compared to 30b. Compound 30d with 5-(R)-ethoxy substituent C5-azide and C5-amine functionalities are significantly less
showed comparable enzyme inhibitory activity. Benzyl ether potent than the corresponding methoxy and hydroxyl deriva-
derivative 30e also showed similar antiviral potency as tives 30b and 30f respectively. Compound 30i with a methyl-
compound 30b. Compound 30f with a 5-(R)-hydroxy group amine substitution is very potent. Compound 30j with an
also showed very potent enzyme inhibitory and antiviral ethylamine functionality showed very potent antiviral activity
activity, however it was 10-fold less potent than compound with an IC50 value of 0.8 nM. The corresponding 4-aminosulfon-
3
0b. Interestingly, inhibitor 30f maintained full antiviral amide derivative 30k, however, showed significant reduction in
R
activity against HIV P20 drug resistant strains of HIV antiviral potency. The propyl amine derivative 30l, with a steri-
DRV
(IC50 = 3.3 nM).
cally demanding alkyl side chain, showed nearly 3-fold
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Table 1 Structure and activity of O-substituted inhibitors
Table 2 Structure and activity of N-substituted inhibitors
a
a,b
a
b
K
i
IC50
K
i
IC50
Entry
1
Inhibitor
(nM)
(nM)
Entry
1
Inhibitor
(nM)
(nM)
1.38
47
0.043
44
2
3
4
5
0.0045
0.037
0.0033
0.012
0.06
0.2
15
2
3
21.4
520
0.008
2.7
nt
4
5
6
0.009
0.8
0.45
3.15
0.0058
0.0073
0.023
22
6
2.8
0.8
a
i
K values represents at least 5 data points. Standard error in all cases
b
i
less than 7%. Darunavir (control) exhibited K = 16 pM. IC50 values
were determined using the MTT assay. Values are means of at least
three experiments. Standard error in all cases less than 5%. Darunavir
exhibited IC50 = 1.6 nM. nt, not tested.
7
reduction in antiviral potency compared to ethylamine deriva-
tive 30j. Compound 30m with a dimethylamine functionality
a
i
K values represents at least 5 data points. Standard error in all cases
b
showed reduction in enzyme K
i
, however it showed 3-fold
less than 7%. Darunavir (control) exhibited K
were determined using the MTT assay. Values are means of at least
i
= 16 pM. IC50 values
improved antiviral activity over its methyl derivative 30i.
In order to obtain molecular insight into the HIV-1 pro- three experiments. Standard error in all cases less than 5%. Darunavir
exhibited IC50 = 1.6 nM.
tease–inhibitor interactions, we have determined X-ray struc-
tures of HIV-1 protease complexed with compounds 30b and
3
0j. A stereoview of 30b-bound HIV-1 protease structure is
shown in Fig. 2. The crystal structure of wild type HIV-1 pro- with the related bis-THF inhibitor bis-THF derived (pdb code:
3
0
tease with inhibitor 30b was determined and refined at 3QAA). As shown, the methoxy group on the Tp-THF ligand
.22 Å resolution. This crystal structure contains the protease forms a water-mediated interaction with the amide NH of
dimer and the inhibitor bound in two orientations related by a Gly48. These interactions likely stabilize the flexible flap
80° rotation with 55/45% relative occupancies. The overall region of the active site cavity. The new interactions with the
structure is similar to the structure of HIV-1 protease with flap region may be responsible for its robust antiviral activity.
1
1
2
9
darunavir with root mean square differences of 0.13 Å for Cα
atoms. Inhibitor 30b has a tetrahydropyrano-tetrahydrofuran bound HIV-1 protease. A stereoview of the active site is shown
Tp-THF) group at P2, which bears a methoxy group. The in Fig. 3. This structure was determined and refined at 1.62 Å
Tp-THF ring shows a slight bend compared to the complex resolution. Similar to the structure for 30b, the structure con-
We have also determined the X-ray crystal structure of 30j-
(
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Fig. 2 Stereoview of the X-ray structure of inhibitor 30b (turquoise color)-bound to the active site of wild-type HIV-1 protease (PDB code: 5DGU).
All strong hydrogen bonding interactions are shown as dotted lines.
Fig. 3 Stereoview of the X-ray structure of inhibitor 30j (green color)-bound to the active site of wild-type HIV-1 protease (PDB code: 5DGW).
All strong hydrogen bonding interactions are shown as dotted lines.
tains the protease dimer and inhibitor 30j is bound in two syntheses of the substituted ligands were carried out in a
orientations related to 180 rotation with 55/45 relative occu- stereoselective manner using a [2,3]-sigmatropic rearrange-
pancies. The structure is related to 30b-bound HIV-1 protease. ment as the key step. A number of inhibitors with alkoxy- and
The major difference is in the binding of the ethylamino sub- alkylamine substituents on the P2 ligands showed excellent
i
stituent on the Tp-THF ring. As it turns out, the amine NH on enzyme K and antiviral IC50 values. Inhibitors with a 5-(R)-
the Tp-THF ring of the inhibitor forms a water-mediated configuration showed improved potency over inhibitors with a
hydrogen bonding interaction with the backbone amide NH of 5-(S)-configuration. Both inhibitors 30b and 30j with a
Gly48. In addition, the amine NH forms a direct hydrogen methoxy and ethylamine functionalities, respectively, dis-
bond with the carbonyl oxygen of Gly48. This interaction is played subnanomolar antiviral activity. Our preliminary
lacking for inhibitor 30b. The ethylamino nitrogen atom in assessment of inhibitor 30f showed that it maintained full
inhibitor 30j shifts its position to enhance the interactions antiviral activity against the HIVDRVP20 resistant HIV-1 variant.
with the wild-type HIV-1 protease. These interactions are likely We have determined high resolution X-ray crystal structures of
to stabilize the flexible flap region of the active site. This may 30b- and 30j-bound HIV-1 protease. The structure of 30b-
help maintain antiviral activity of the inhibitor against multi- bound HIV-1 protease revealed that the methoxy oxygen forms
drug-resistant HIV-1 variants.
a strong water-mediated hydrogen bond with the amide NH of
Gly48 located in the flap region of the HIV-1 protease active
site. The ethylamino group in inhibitor 30j also forms a water-
mediated interaction with Gly48. In addition, the amine NH
forms a direct hydrogen bond with Gly48 carbonyl oxygen.
Conclusion
In summary, we have designed and synthesized alkoxy- and The ethyl side chain also nicely packed in the hydrophobic
amine-substituted derivatives of a tetrahydropyran-tetrahydro- pocket in the S2-subsite. The basic amine functionality on the
furanyl ligand. These molecules are specifically designed to inhibitor may be important for improving pharmacological
make hydrogen bonding interactions with the flap region of properties. More detailed drug-resistance studies as well as
HIV-1 protease. In addition, the alkyl substituents are expected further optimization of enzyme–inhibitor interactions are
to make hydrophobic interactions in the S2 subsite. The currently in progress.
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mixture was warmed to room temperature. The reaction was
stirred until both layers were clear. The organic layer was
Experimental section
All reactions were carried out under an inert atmosphere, separated and the aqueous layer was extracted with dichloro-
either N or Ar, using magnetic stirring and oven-dried glass- methane (3 × 15 mL). The organic layers were combined,
2
ware. All solvents were anhydrous and distilled prior to use. washed with brine and dried over MgSO . The solid was fil-
4
Dichloromethane and triethylamine were distilled from tered out and the organic layer was concentrated under
calcium hydride. Tetrahydrofuran, diethyl ether, and benzene vacuum. The crude mixture was purified on silica gel using
were distilled from sodium/benzophenone. All other solvents 20% ethyl acetate/hexanes to obtain the desired allyl alcohol
were HPLC grade or better. Flash column chromatography was (9.4 g, 98% yield) as a colorless oil. R
f
= 0.27 (40%
1
performed using EM Science 60–200 mesh silica gel. Thin- ethyl acetate/hexanes). H NMR (300 MHz, Chloroform-d)
layer chromatography was performed using 60 F-254 E. Merck δ 5.78–5.74 (m, 1H), 5.50 (ddt, J = 11.2 Hz, 7.0 Hz, 1.3 Hz, 1H),
1
13
silica gel plates. H- and C-NMR were recorded using Bruker 4.78–4.62 (m, 1H), 4.24 (dd, J = 12.9 Hz, 7.0 Hz, 1H), 4.20–4.08
AV-400 MHz, Avance DRX-500, Varian Mercury-Vx-300, and (m, 1H), 4.00 (td, J = 12.2 Hz, 2.8 Hz, 1H), 3.83 (ddd, J = 11.8
Gemini-2300 spectrometers and use Me Si as an internal stan- Hz, 5.4 Hz, 1.5 Hz, 1H), 2.47–2.27 (m, 1H), 1.86–1.63 (m, 1H),
4
1
3
dard. Optical rotations were recorded on a Perkin-Elmer 341 1.55 (s, 3H), 1.48–1.45 (m, 1H), 1.39 (s, 3H). C NMR (75 MHz,
polarimeter. A Thermo Finnigan LCQ Classic mass was used CDCl
for MS analyses. The purity of test compounds was determined
3
) δ 132.3, 131.5, 98.5, 65.7, 59.6, 58.8, 31.2, 29.9, 19.1
To a round bottom flask charged with activated molecular
by HRMS and HPLC analysis. All test compounds showed sieves (6.0 g) was added a solution of substrate, (S,Z)-3-
≥95% purity.
(2,2-dimethyl-1,3-dioxan-4-yl)prop-2-en-1-ol (9.0 g, 52.0 mmol)
in acetonitrile (150 mL), followed by t-butylbromoacetate
(S,Z)-Ethyl 3-(2,2-dimethyl-1,3-dioxan-4-yl)acrylate (6)
(
9.90 mL, 67.2 mmol), tetrabutylammonium iodide (2.0 g,
To a solution of (S)-methyl 2,2-dimethyl-1,3-dioxane-4-carboxy- 5.2 mmol) and cesium hydroxide monohydrate (13.1 g,
late (5) (3.0 g, 17.2 mmol) in CH Cl (100 mL) at −78 °C was 78.0 mmol) at room temperature. The reaction was allowed to
2
2
2 2
added Dibal-H (1 M in CH Cl , 19.0 mL). The solution was stir for 6 h. The solid was filtered out and the solvent was con-
allowed to warm slowly to −50 °C over 1 h. Upon completion, centrated under vacuum; the residue was purified by flash
methanol (100 mL) was added to the reaction followed by column chromatography (5% ethyl acetate/hexanes) to afford 7
Ph
allowed to stir for 1 h at 0 °C. The reaction was concentrated acetate/hexanes). [α]23 = +22.9 (c 1.29, CHCl
under vacuum and the solid was washed with CH Cl2 (3 × (300 MHz, Chloroform-d) δ 5.72–5.51 (m, 2H), 4.77–4.65
3 2 f
PCHCO Et (4.20 g, 12.1 mmol) and the reaction was (14.4 g, 97% yield) as a colorless oil. R = 0.57 (30% ethyl
D
1
3
)
H NMR
2
2
0 mL) and concentrated under vacuum. The crude mixture (m, 1H), 4.26–4.09 (m, 2H), 4.01 (dd, J = 17.3, 2.6 Hz, 1H), 3.93
was purified on silica gel using 5–10% ethyl acetate/hexanes. (d, J = 3.6 Hz, 2H) 3.82 (ddd, J = 11.8 Hz, 5.4 Hz, 1.4 Hz, 1H),
The desired product 6 was obtained as a separable mixture of 1.79–1.65 (m, 1H), 1.48 (s, 3H), 1.46 (s, 10H), 1.37 (s, 3H).
1
3
cis/trans (8 : 1) isomers (2.6 g, 70% yield). cis: R
ethyl acetate/hexanes). [α]23 = −12.5 (c 1.01, CHCl
(
f
= 0.38 (10%
C NMR (75 MHz, CDCl
3
) δ 169.5, 134.1, 127.7, 98.3, 81.5,
D
1
3
). H NMR 67.6, 66.8, 65.5, 59.5, 31.1, 29.9, 28.0, 19.1; LRMS-ESI (m/z):
300 MHz, Chloroform-d) δ 6.17 (dd, J = 11.4 Hz, 7.1 Hz, 1H), 438.4 (M + Na) .
+
5
.76 (d, J = 11.7 Hz, 1H), 5.52 (q, J = 7.1 Hz, 1H), 4.24–4.10
(
2
2S,3S)-t-Butyl 3-((S)-2,2-dimethyl-1,3-dioxan-4-yl)-
-hydroxypent-4-enoate (9)
) δ 165.7, 149.7, 119.2, A solution of LiHMDS (84.0 mL 1.0 M in THF, 84.0 mmol) was
8.3, 66.8, 60.2, 59.5, 30.0, 29.4, 19.3, 14.2. trans: R = 0.20 added to a cold solution (−60 °C) of 7 (12.0 g, 42.0 mmol) in
(q, J = 7.5 Hz, 2H), 4.10–3.97 (m, 1H), 3.90–3.76 (d, J = 16 Hz,
1
7
9
H), 1.67–1.61 (m, 2H), 1.50 (s, 3H), 1.39 (s, 3H), 1.28 (t, J =
.1 Hz, 3H). C NMR (75 MHz, CDCl
1
3
3
f
1
(10% ethyl acetate/hexanes). H NMR (400 MHz, Chloroform-d) THF (250 mL) (LiHMDS was added at a rate that did not
δ 6.86 (dd, J = 15.7 Hz, 7.1 Hz, 1H), 6.04 (d, J = 11.8 Hz, 1H), exceed −50 °C). The reaction mixture was allowed to warm
4
2
.27–4.08 (q, J = 7.5 Hz, 2H), 4.01 (ddt, J = 14.9 Hz, 8.3 Hz, slowly to −20 °C over 2 h. The reaction was quenched with
.7 Hz, 1H), 3.90–3.76 (m, 1H), 3.76–3.59 (m, 1H), 1.82–1.60 saturated ammonium chloride (10 mL) extracted with ethyl
(
7
m, 1H), 1.60–1.50 (m, 1H), 1.48 (s, 3H), 1.41 (s, 3H), 1.28 (t, J = acetate (3 × 20 mL) after warming to room temperature. The
1
3
3
.1 Hz, 3H). C NMR (101 MHz, CDCl ) δ 166.4, 147.0, 120.3, organic layers were combined washed with brine, dry over
1
08.6, 98.5, 67.8, 60.3, 59.5, 30.4, 29.7, 19.0, 14.1; LRMS-CI anhydrous MgSO and reduce under vacuum. The residue was
4
+
(
m/z): 215 (M + H) .
purified with a 5–10% gradient of ethyl acetate/hexanes. The
desired 9 (9.0 g, 77% yield, 8.5 : 1 mixture of diastereomers)
(S,Z)-t-Butyl-2-(3-(2,2-dimethyl-1,3-dioxan-4-yl)allyloxy)-
was obtained as a colorless oil. R = 0.30 (20% ethyl acetate/
f
acetate (7)
D
1
hexanes). [α]23 = +5.8 (c 1.02, CHCl
3
); H NMR (300 MHz,
Diisobutyl aluminum hydride (1 M in CH Cl , 27.5 mL, Chloroform-d) δ 5.86–5.74 (m, 1H), 5.26–5.01 (dd, J = 12.1 Hz,
2 2
2
(
7.5 mmol) was slowly added to a cold solution (−78 °C) of 6 2H), 4.23 (t, J = 4.23 Hz, 1H), 4.12 (m, 1H), 3.99 (td, J = 11.9 Hz,
12.0 g, 56.0 mmol) in dichloromethane (200 mL). The solu- 2.8 Hz, 1H), 3.86 (dd, J = 11.1 Hz, 4.9 Hz, 1H), 3.15 (d, J =
tion was allowed to stir for 15 min at −78 °C. A saturated solu- 4.2 Hz, 1H), 2.48–2.45 (m, 1H), 1.90–1.64 (m, 1H), 1.45 (d, J =
1
3
tion of Rochelle’s salt (50 mL) was added and the reaction 4.7 Hz, 13H), 1.35 (s, 3H). C NMR (75 MHz, CDCl ) δ 172.8,
3
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1
1
33.1, 119.3, 98.5, 82.5, 71.0, 69.3, 59.8, 52.2, 29.8, 28.6, 28.1, mixture to remove the excess ozone. Dimethyl sulfide
−
+
9.2; LRMS-ESI (m/z); 309.3 (M + Na) .
Minor isomer 10
(0.50 mL, 6.9 mmol) was added to the reaction and the
mixture was warmed to room temperature and stirred an
= −17.5 (c 1.8, additional 3 h. p-TsOH (10.0 mg, 5 mol%) was added and the
2
3
R
f
= 0.37 (20% ethyl acetate/hexanes) [α]
D
1
CHCl ) H NMR (300 MHz, Chloroform-d) δ 5.69–5.51 (m, 1H), reaction mixture was stirred for 16 h. The reaction was again
3
5
.20–5.04 (m, 2H), 4.46 (dd, J = 5.1 Hz, 2.2 Hz, 1H), 4.08–3.80 carefully concentrated and the residue was purified on silica
(
m, 3H), 2.94 (d, J = 5.2 Hz, 1H), 2.40 (td, J = 9.8 Hz, 2.2 Hz, gel (20% ether/hexanes to 40% ether/hexanes) to afford com-
1
3
1
1
1
H), 1.53–1.34 (m, 17H). C NMR (75 MHz, CDCl ) δ 174.1, pound 12, (0.22, 70% yield) as a white solid. R = 0.23 (70%
3
f
D
1
32.1, 119.9, 98.6, 82.4, 69.0, 67.0, 60.1, 53.9, 30.0, 29.9 28.1, ethyl acetate/hexanes). [α]23 = −34.2 (c 1.4, CHCl
3
); H NMR
(400 MHz, Chloroform-d) δ 4.97 (d, J = 3.4 Hz, 1H), 4.26–4.09
m, 2H), 4.01–3.82 (m, 2H), 3.42–3.20 (m, 1H), 2.49 (m, 1H),
.20 (bs, 1H), 2.09–1.98 (m, 1H), 1.94–1.82 (m, 1H), 1.82–1.58
−
+
9.2; LRMS-ESI (m/z): 309.3 (M + Na) .
(
2
(
R)-3-((S)-2,2-Dimethyl-1,3-dioxan-4-yl)pent-4-en-1-ol (11)
1
3
To a cold (0 °C) THF (25 mL) solution of 9 (0.98 g, 3.42 mmol) (m, 2H). C NMR (100 MHz, CDCl
was added triethyl amine (0.57 mL, 4.10 mmol) followed by 46.3, 29.3, 21.8.
MsCl (0.32 mL, 4.1 mmol). The reaction was stirred for 2 h at
3
) δ 101.3, 68.4, 67.3, 61.1,
(
2
2S,3R)-t-Butyl 3-((S)-2,2-dimethyl-1,3-dioxan-4-yl)-
-methoxypent-4-enoate (13)
The organic layers were combined and dried over anhydrous To a cold (0 °C) solution of 11 (0.18 g, 0.63 mmol) and methyl
MgSO . The solvent was concentrated under vacuum and the iodide (50 µL, 0.75 mmol) in THF (5 mL) was added sodium
0
°C. The reaction was quenched with saturated ammonium
chloride (10 mL) then extracted with ethyl acetate (3 × 15 mL).
4
crude mixture was purified using 10% ethyl acetate/hexanes to hydride (20 mg, 0.8 mmol). The reaction was allowed to stir for
obtain the desired mesylated compound (1.2 g, 99% yield) as a 2 h at 23 °C then quenched with saturated ammonium chlor-
1
colorless oil. R
f
= 0.37 (20% ethyl acetate/hexanes). H NMR ide (5 mL). The reaction mixture was extracted with ethyl
(400 MHz, Chloroform-d) δ 5.77 (dt, J = 17.2 Hz, 9.9 Hz, 1H), acetate (3 × 10 mL). The organic layers were combined, washed
5
4
.20 (dd, J = 21.0 Hz, 12.9 Hz, 2H), 5.06 (d, J = 4.1 Hz, 1H), with brine and dried over anhydrous sodium sulfate. The
.07–4.01 (m, 1H), 4.01–3.92 (m, 1H), 3.89–3.81 (m, 1H), 3.15 solvent was reduced under vacuum and the residue was puri-
(
1
s, 3H), 2.66–2.61 (m, 1H), 1.74 (qd, J = 12.3 Hz, 5.5 Hz, 1H), fied on silica gel to obtain 13 (0.17 g, 90% yield) as a colorless
1
3
1
.48 (s, 10H), 1.43 (s, 3H), 1.36 (s, 3H). C NMR (100 MHz, oil. R
) δ 167.2, 132.0, 120.4, 98.6, 83.4, 78.0, 68.1, 59.7, 51.0, Chloroform-d) δ 5.78 (dt J = 17.2 Hz, 9.5 Hz, 1H), 5.21–5.00
9.4, 29.7, 28.2, 28.0, 19.0. (m, 2H), 4.03–3.88 (m, 2H), 3.84 (ddd, J = 11.7 Hz, 5.5 Hz,
f
= 0.54 (20% ethyl acetate/hexanes. H NMR (400 MHz,
CDCl
3
3
3
The mesylated compound above was dissolved (1.23 g, 1.7 Hz, 1H), 3.79 (d, J = 4.7 Hz, 1H), 3.36 (s, 3H), 2.45 (dt, J =
.39 mmol) in THF (20 mL). At 0 °C lithium aluminum 10.1 Hz, 5.3 Hz, 1H), 1.82–1.69 (m, 1H), 1.47 (m, 9H), 1.42
1
3
hydride (0.54 g, 14.2 mmol) was added and the reaction was (s, 3H),1.35 (m, 3H). C NMR (101 MHz, CDCl ) δ 170.6,
3
stirred for 1 h at 0 °C then stirred for 6 h at room temperature. 134.0, 118.8, 98.4, 81.5, 80.4, 68.5, 59.9, 58.2, 52.0, 29.8, 28.5,
A small aliquot of the reaction was quenched and checked by 28.2, 19.13.
NMR to determine the reaction’s progress. The reaction was
(
1
2R,3R)-1-t-Butoxy-3-((S)-2,2-dimethyl-1,3-dioxan-4-yl)-
-oxopent-4-en-2-yl4-nitrobenzoate (15)
1 mL). The reaction was stirred until a white precipitate Into a cold (0 °C) solution of 9 (0.15 g, 0.52 mmol) in THF
formed. MgSO was added to the solution and the white solid (10 mL) was added triphenylphosphine (0.55 g, 2.1 mmol)
cooled to 0 °C and diluted with ethyl acetate. This was fol-
lowed by the stepwise addition of 3 N NaOH (0.5 mL) and H
2
O
(
4
was filtered out. The solvent was removed under vacuum and p-nitrophenylbenzoic acid (0.35 g, 2.1 mmol) and diethyl azo-
the crude was purified by flash column chromatography (gra- dicarboxylate (0.95 µL, 2.1 mmol). The reaction was allowed to
dient 10%–20% ethyl acetate/hexanes) to give 11 (0.46 g, 70% stir 36 h. The reaction was diluted with ethyl acetate (10 mL)
f
yield, 2 steps) as a colorless oil. R = 0.45 (50% ethyl acetate/ and quenched with a saturated solution of sodium bicarbonate
2
3
1
hexanes). [α] = −29.2 (c 1.4, CHCl3); H NMR (400 MHz, (10 mL). The reaction was extracted with ethyl acetate (3 ×
D
Chloroform-d) δ 5.75 (m, 1H), 5.20–5.00 (m, 2H), 4.01–3.86 15 ml). The organic layers were combined, washed with brine
(m, 2H), 3.97–3.87 (m, 1H), 3.85–3.80 (m, 1H), 3.69–3.57 and dried over anhydrous sodium sulfate. The solvent was con-
(
1
(
3
m, 1H), 2.36–2.22 (m, 1H), 2.13 (bs, 1H), 1.86–1.59 (m, 2H), centrated under vacuum and the crude mixture was purified
1
3
.44 (s, 3H), 1.37 (s, 3H), 1.34–1.21 (m, 2H). C NMR on silica gel using 5% ethyl acetate/hexanes to obtain 15
) δ 138.1, 117.0, 98.4, 71.4, 60.8, 59.87, 46.0, (0.21 g, 91%) as a pale yellow solid. R = 0.36 (10% ethyl
100 MHz, CDCl
3.5, 29.8, 27.5, 19.1; LRMS-CI (m/z): 201.0 (M + H) .
3
f
+
D
3
1
acetate/hexanes). [α]2 = −0.27 (c 1.1, CHCl3). H NMR
(
1
300 MHz, Chloroform-d) δ 8.36–8.21 (m, 4H), 5.86 (dt, J =
7.2 Hz, 10.0 Hz, 1H), 5.32–5.09 (m, 2H), 4.24 (dt, J = 11.8 Hz,
Into a cold a solution of 11 (0.45 g, 2.25 mmol) in CH Cl / 2.7 Hz, 1H), 3.97 (td, J = 12.0 Hz, 2.8 Hz, 1H), 3.89–3.73
(
3aS,4S,7aR)-hexahydro-2H-furo[2,3-b]pyran-4-ol (12)
2
3
MeOH (20 mL, 4 : 1) at −78 °C was bubbled a stream of ozone (m, 1H), 2.65 (td, J = 9.5 Hz, 2.9 Hz, 1H), 1.93–1.74 (m, 1H),
1
3
until a blue color persisted. The ozone stream was stopped 1.44 (s, 9H), 1.34 (s, 3H), 1.27 (s, 3H). C NMR (75 MHz,
and a stream of argon was bubbled through the reaction CDCl ) δ 168.3, 163.8, 150.68, 134.9, 132.3, 130.8, 123.6, 120.4,
3
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9
8.4, 82.8, 73.6, 66.6, 59.7, 50.9, 29.6, 28.4, 28.0, 18.8; 119.9, 98.2, 81.4, 78.4, 72.5, 65.8, 59.9, 52.4, 29.8, 28.3,
+
LRMS-ESI (m/z); 481.5 (M + Na) .
28.1, 19.1.
(
4
3S,3aS,4S,7aS)-3-Methoxyhexahydro-2H-furo[2,3-b]pyran-
-ol (14)
To a cold (0 °C) solution of 13 (0.14 mg, 0.47 mmol) in THF
5 mL) was added lithium aluminum hydride (41 mg,
.03 mmol). The reaction was allowed to stir for 1 h at 23 °C
after which the reaction was cooled to 0 °C and quenched by
adding excess ethyl acetate, 1 N NaOH (0.5 mL), H O (0.5 mL).
(
2
2R,3R)-t-Butyl 3-((S)-2,2-dimethyl-1,3-dioxan-4-yl)-
-methoxypent-4-enoate (16)
To a cold (0 °C) solution of 15 (0.42 g, 0.96 mmol) in methanol
was added potassium carbonate (0.16 g, 1.16 mmol). The reac-
tion was allowed to stir for 0.5 h. The reaction was quenched
with a saturated ammonium chloride (5 mL) and the methanol
was removed under vacuum. The solution was extracted with
ethyl acetate (3 × 10 mL) and the combined organic layer was
combined, washed with brine and dried over anhydrous
sodium sulfate. The solvent was removed under vacuum and
the residue was purified on silica gel using 10% ethyl acetate/
hexanes to obtain the free secondary alcohol (0.28 mg, 99%
(
1
2
After a white precipitate formed magnesium sulfate was added
and stirred for 15 min. The reaction mixture was filtered and
concentrated under vacuum to provide the corresponding diol.
1
H NMR (400 MHz, Chloroform-d) δ 5.87 (dt, J = 17.3 Hz,
9
1
.6 Hz, 1H), 5.19 (dd, J = 10.3 Hz, 2.0 Hz, 1H), 5.10 (ddd, J =
7.2 Hz, 2.0, 0.6 Hz, 1H), 4.13 (dt, J = 11.9 Hz, 2.6 Hz, 1H), 3.95
yield) as an amorphous solid. R = 0.38 (30% ethyl acetate/
f
(
td, J = 12.1 Hz, 2.8 Hz, 1H), 3.79 (ddd, J = 11.7 Hz, 5.4 Hz,
D
3
1
hexanes). [α]2 = −21.6 (c 1.1, CHCl3). H NMR (400 MHz,
1
2
1
.6 Hz, 1H), 3.74–3.55 (m, 2H), 3.38 (s, 3H), 3.31–3.28 (m, 1H),
.71 (bs, 1H), 2.37–2.32 (m, 1H), 1.80 (qd, J = 12.5 Hz, 5.5 Hz,
H), 1.44 (s, 3H), 1.34 (s, 3H), 1.22 (m, J = 13.2 Hz, 1H).
Chloroform-d) δ 5.92 (dt, J = 17.2 Hz, 10.0 Hz, 1H), 5.29–5.03
(m, 2H), 4.22 (dt, J = 11.8 Hz, 2.8 Hz, 1H), 4.11 (dd, J = 8.9 Hz,
6
1
.2 Hz, 1H), 3.95 (td, J = 12.1 Hz, 2.8 Hz, 1H), 3.80 (ddd, J =
1.7, 5.4, 1.6 Hz, 1H), 3.28 (d, J = 9.1 Hz, 1H), 2.32–2.27
1
3
3
C NMR (100 MHz, CDCl ) δ 134.8, 118.8, 98.3, 82.7, 67.0,
61.0, 59.9, 57.7, 50.4, 29.7, 28.6, 19.0.
(
(
m, 1H), 1.85–1.74 (m, 1H), 1.46 (s, 9H), 1.44 (s, 3H), 1.35
s, 3H), 1.19 (d, J = 13.0 Hz, 1H). C NMR (100 MHz, CDCl3)
The crude diol. mixture was taken up in CHCl /MeOH (4 : 1)
1
3
3
and a stream of O was bubble through the solution at −78 °C
3
δ 173.1, 134.1, 118.8, 98.5, 82.1, 73.0, 68.6, 59.7, 52.5, 29.7,
until a blue color persisted. Argon was bubbled through the
blue solution until the solution became clear. Dimethyl sulfide
2
8.4, 28.1, 18.9.
To cold (0 °C) solution of (2R,3S)-t-Butyl 3-((S)-
a
(
0.13 mL, 5.0 eq.) was added to the reaction and the mixture
was warmed to room temperature and stirred an additional
h. To the reaction mixture was added p-TsOH (10 mol%) the
2
0
,2-dimethyl-1,3-dioxan-4-yl)-2-hydroxypent-4-enoate (0.12 g,
.40 mmol) in THF (5 mL) was added sodium hydride
3
(20.0 mg, 0.8 mmol) followed by methyl iodide (50 µL,
mixture was stirred for 18 h at room temperature. The reaction
was carefully concentrated and the residue was purified on
silica gel (20% ether/hexanes to 50% ether/hexanes) to afford
0
.8 mmol). The reaction was allowed to stir for 2 h at 23 °C
then quenched with saturated ammonium chloride (5 mL).
The reaction mixture was extracted with ethyl acetate (3 ×
1
f
4, (24 mg, 30% yield 2 steps) as a colorless oil. R = 0.20 (60%
1
0 mL). The organic layers were combined, washed with brine
D
1
ethyl acetate/hexanes). [α]23 = −111.7 (c 1.2, CHCl
3
); H NMR
and dried over anhydrous sodium sulfate. The solvent was
reduced under vacuum and the residue was purified on silica
(
(
(
400 MHz, Chloroform-d) δ 4.99 (d, J = 4.1 Hz, 1H), 4.24–4.17
m, 1H), 4.17–4.14 (m, 2H), 4.14–4.02 (m, 1H), 4.01–3.96
m, 1H), 3.43–3.37 (d, J = 13.6 Hz, 1H), 3.32 (s, 3H), 2.74 (d, J =
gel to obtain 16 (0.12 g, 96% yield) as a colorless oil. R
(
f
= 0.54
20% ethyl acetate/hexanes. H NMR (300 MHz, Chloroform-d)
δ 5.74 (dt, J = 17.2 Hz, 10.1 Hz, 1H), 5.22–4.93 (m, 2H), 4.29
1
1
0.1 Hz, 1H), 2.53–2.48 (m, 1H), 2.00–1.85 (m, 1H), 1.80–1.74
1
3
(
m, 1H). C NMR (100 MHz, CDCl
0.7, 57.7, 47.5, 33.0.
3
) δ 101.5, 80.7, 73.3, 67.3,
(
(
(
(
d, J = 11.9 Hz, 1H), 3.95 (td, J = 12.0 Hz, 2.8 Hz, 1H), 3.83–3.73
m, 2H), 3.35 (s, 3H), 2.26 (td, J = 9.9 Hz, 2.2 Hz, 1H), 1.79–1.71
m, 1H), 1.43 (s, 9H), 1.41 (s, 3H), 1.35 (s, 3H), 1.19–1.07
6
(
4
3R,3aS,4S,7aS)-3-Methoxyhexahydro-2H-furo[2,3-b]pyran-
-ol (19)
1
3
3
m, 1H). C NMR (75 MHz, CDCl ) δ 171.3, 132.9, 119.8, 98.2,
8
1.5, 80.5, 65.9, 60.0, 58.1, 52.3, 29.8, 28.4, 28.1, 19.1.
Methyl ether derivative 19 was obtained by following the two-
step procedures outlined above for the formation of compound
(
4
2R,3R)-t-Butyl 2-(benzyloxy)-3-((S)-2,2-dimethyl-1,3-dioxan-
-yl)pent-4-enoate (18)
1
4. Methyl ether 19 was obtained in 45% yield. R
f
= 0.20 (70%
1
ethyl acetate/hexanes). H NMR (300 MHz, Chloroform-d)
Compound 18 was prepared by following the procedure out- δ 5.06 (d, J = 3.8 Hz, 1H), 4.38–4.22 (m, 2H), 4.21–4.13 (m, 1H),
lined for o-alkylation outlined above. Compound 18 was 3.94–3.86 (m, 3H), 3.33 (s, 3H), 2.53–2.47 (m, 2H), 1.92–1.76
1
3
obtained in 88% yield. R = 0.70 (20% ethyl acetate/hexanes). (m, 1H), 1.76–1.54 (m, 1H). C NMR (75 MHz, CDCl ) δ 101.4,
f
3
1
H NMR (300 MHz, Chloroform-d) δ 7.43–7.27 (m, 5H), 5.76 78.9, 72.2, 66.3, 60.5, 57.9, 51.1, 30.2.
(
1
(
dt, J = 17.2 Hz, 10.1 Hz, 1H), 5.24–4.94 (m, 2H), 4.58 (d, J =
1.3 Hz, 1H), 4.48–4.28 (m, 2H), 3.99–3.89 (m, 2H), 3.86–3.70
m, 1H), 2.37 (td, J = 10.0 Hz, 2.1 Hz, 1H), 1.82–1.68 (m, 1H),
(
4
3R,3aS,4S,7aS)-3-Ethoxyhexahydro-2H-furo[2,3-b]pyran-
-ol (20)
1
.44 (s, 9H), 1.37 (s, 3H), 1.33 (s, 3H) 1.15 (d, J = 12.9, 1H). Ethyl ether derivative 20 was prepared by following the two-
1
3
C NMR (75 MHz, CDCl ) δ 171.2, 137.4, 132.8, 128.3, 127.9, step procedures described for compound 19. Ethyl ether 20
3
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was obtained in 60% yield. R
hexanes). H NMR (400 MHz, Chloroform-d) δ 5.05 (d, J = desired azide (1.6 g, 70% yield). R = 0.35 (10% ethyl acetate/
f
= 0.20 (50% ethyl acetate/ trated under vacuum and purified on silica gel to get the
1
f
D
1
3
(
3
.8 Hz, 1H), 4.45–4.26 (m, 2H), 4.26–4.07 (m, 1H), 4.01–3.87 hexanes). [α]23 = +16.3 (c 1.6, CHCl
m, 1H), 3.85 (dd, J = 8.6 Hz, 4.7 Hz, 1H), 3.59–3.41 (m, 2H), Chloroform-d) δ 7.56–7.39 (m, 6H), 7.38–7.13 (m, 10H), 5.48
.32 (td, J = 11.9 Hz, 2.3 Hz, 1H), 2.64–2.41 (m, 2H), 1.91–1.78 (dt, J = 17.3 Hz, 10.1 Hz, 1H), 4.96 (dd, J = 10.3 Hz, 1.9 Hz, 1H),
3
). H NMR (400 MHz,
13
(m, 1H), 1.78–1.64 (m, 1H), 1.19 (t, J = 7.0 Hz, 3H). C NMR 4.84 (dd, J = 17.3 Hz, 1.8 Hz, 1H), 4.30 (dt, J = 11.9 Hz, 2.4 Hz,
(
3
100 MHz, CDCl
0.2, 15.5.
3
) δ 101.3, 77.1, 72.6, 66.6, 66.0, 60.7, 50.8, 1H), 3.98 (td, J = 12.1 Hz, 2.7 Hz, 1H), 3.88–3.71 (m, 1H),
3.69–3.64 (m, 1H), 3.38 (dd, J = 10.1 Hz, 2.6 Hz, 1H), 3.07 (dd,
J = 10.0 Hz, 7.9 Hz, 1H), 1.98 (td, J = 10.2 Hz, 2.2 Hz, 1H),
(
4
3R,3aS,4S,7aS)-3-(Benzyloxy)hexahydro-2H-furo[2,3-b]pyran-
-ol (21)
Benzyl ether derivative 21 was prepared by following the two- 119.6, 98.4, 87.0, 67.2, 65.4, 62.3, 59.9, 50.5, 29.7, 28.4, 18.9.
step procedures as described for compound 19. Benzyl ether (S)-4-((3S,4R)-4-Azido-5-(trityloxy)pent-1-en-3-yl)-2,2-dimethyl-
1 was obtained in 88% yield. [α]2 = +45 (c 1.1, CHCl ); R = 1,3-dioxane (0.08 g, 0.17 mmol) was taken up in CH Cl /MeOH
1
.81–1.59 (m, 1H), 1.49 (s, 3H), 1.35 (s, 3H), 1.20–1.03 (m, 1H).
13
C NMR (100 MHz, CDCl ) δ 143.8, 133.6, 128.6, 127.8, 127.0,
3
D
2
0
3
3
f
2
3
1
3
.22 (60% ethyl acetate/hexanes). H NMR (300 MHz, Chloro- (20 ml, 4 : 1) and a stream of O was bubble through the solu-
form-d) δ 7.47–7.18 (m, 5H), 5.05 (d, J = 3.7 Hz, 1H), 4.51 (d, J = tion at −78 °C until a blue color persisted. Argon was bubbled
1
1
2
.6 Hz, 2H), 4.49–4.36 (m, 1H), 4.26 (dd, J = 9.0 Hz, 6.8 Hz, through the blue solution until the solution became clear.
H), 4.21–4.06 (m, 1H), 3.93–3.85 (m, 2H), 3.31 (td, J = 11.8 Hz, Dimethyl sulfide (0.5 mL) was added to the reaction and the
.4 Hz, 1H), 2.66–2.54 (m, 1H), 2.49 (bs, 1H), 1.93–1.75 mixture was warmed to room temperature and stirred an
1
3
(m, 1H), 1.75–1.47 (m, 1H). C NMR (75 MHz, CDCl ) δ 137.4, additional 3 h. To the reaction mixture was added p-TsOH
3
1
28.5, 128.0, 128.0, 101.3, 72.7, 72.5, 66.4, 60.6, 51.2, 30.1.
(10 mol%) the mixture was stirred for 18 h at room tempera-
ture. The reaction was carefully concentrated and the residue
was purified on silica gel (20% ether/hexanes to 50% ether/
(2S,3S)-3-((S)-2,2-Dimethyl-1,3-dioxan-4-yl)-1-(trityloxy)pent-
4
-en-2-ol (22)
hexanes) to afford 23, (23 mg, 74% yield) as a white solid. R
f
=
).
D
To a cold (0 °C) solution of 9 (1.50 g, 5.30 mmol) in THF 0.33 (50% ethyl acetate/hexanes). [α]23 = −20.4 (c 1.0, CHCl
3
1
(30 mL) was added lithium aluminum hydride (0.45 g,
H NMR (400 MHz, Chloroform-d) δ 5.07 (d, J = 3.7 Hz, 1H),
1
1.7 mmol). The reaction was allowed to stir for 1 h at 23 °C 4.42–4.27 (m, 2H), 4.21 (dt, J = 10.9 Hz, 5.7 Hz, 1H), 3.90 (ddd,
after which the reaction was cooled to 0 °C and quenched by J = 12.2 Hz, 4.3 Hz, 2.3 Hz, 1H), 3.83–3.71 (m, 1H), 3.32 (td, J =
adding excess ethyl acetate, 1 N NaOH (0.5 mL), H O (0.5 mL). 12.0 Hz, 2.0 Hz, 1H), 2.63–2.45 (m, 2H), 1.79 (ddd, J = 13.2 Hz,
2
1
3
After a white precipitate formed magnesium sulfate was added 3.8 Hz, 1.6 Hz, 1H), 1.69 (td, J = 11.6 Hz, 4.5 Hz, 1H). C NMR
and stirred for 15 min. The reaction mixture was filtered and (100 MHz, CDCl ) δ 101.7, 72.3, 65.5, 60.8, 59.0, 52.01, 29.8;
3
+
concentrated under vacuum.
LRMS-CI (m/z); 186.0 (M + H) .
2 2
The crude 1,2-diol was dissolved in CH Cl (20.0 mL). To
that mixture was added triethyl amine (1.6 mL, 11.1 mmol)
General procedure for the synthesis of N-alkylated ligands
and triphenylmethyl chloride (1.6 g, 5.83 mmol). The reaction (3R,3aS,4S,7aS)-3-azidohexahydro-2H-furo[2,3-b]pyran-4-ol was
was allowed to stirr for 24 h. Upon completion the reaction dissolved in a solution methanol and placed under argon. 10%
was concentrated under vacuum and purified on silica gel to Palladium on carbon (10 mol%) was added and the mixture
obtain the 22. (2.20 g, 92% yield) as a white solid. R = 0.30 was stirred under a hydrogen balloon for 1 h. Upon com-
f
D
(
20% ethyl acetate/hexanes). [α]23 = −1.86 (c 1.5, CHCl
3
). pletion the reaction was filtered through a plug of silica. The
1
H NMR (400 MHz, Chloroform-d) δ 7.48–7.39 (m, 6H), solvent was removed under vacuum and the product was used
.35–7.18 (m, 10H), 5.85 (dt, J = 17.4 Hz, 10.1 Hz, 1H), 5.16 without further purification.
dd, J = 10.3 Hz, 2.1 Hz, 1H), 4.99 (dd, J = 17.3 Hz, 2.1 Hz, 1H), The amino alcohol obtained from the previous step was dis-
.17–3.98 (m, 2H), 3.93 (td, J = 12.1 Hz, 2.7 Hz, 1H), 3.79 (dd, solved in methanol and treated with benzaldehyde (1.0 eq.)
J = 11.2 Hz, 4.8 Hz, 1H), 3.21–3.06 (m, 2H), 3.04 (d, J = 1.1 Hz, and sodium triacetoxyborohydride (1.2 eq.). The reaction was
7
(
4
1
5
H), 2.30 (dt, J = 9.8 Hz, 3.3 Hz, 1H), 1.80 (dd, J = 12.5 Hz, allowed to stir for 18 h (or until the starting material was con-
.3 Hz, 1H), 1.30 (d, J = 5.5 Hz, 6H), 1.29–1.15 (m, 1H). sumed). The desired aldehyde (1.5 eq.) was added followed by
1
3
C NMR (100 MHz, CDCl ) δ 144.0, 128.7, 127.8, 127.0, 119.8, additional sodium triacetoxyborohydride (1.5 eq.) and the reac-
3
9
8.2, 86.5, 73.0, 71.2, 64.9, 59.8, 50.9, 29.8, 28.7, 19.0; tion was allowed to continue for an additional 12 h to give the
+
LRMS-ESI (m/z); 481.5 (M + Na) .
desired dialkylated amino-Tp-THF ligand.
3R,3aS,4S,7aS)-3-(Benzyl(methyl)amino)hexahydro-2H-furo-
2,3-b]pyran-4-ol (24). Tertiary amine 24 was prepared follow-
(
(3R,3aS,4S,7aS)-3-Azidohexahydro-2H-furo[2,3-b]pyran-4-ol (23)
[
To a solution of 22 (2.2 g, 4.80 mmol) in THF (50.0 mL) at 0 °C ing the general procedure outlined above. Amine 24 was
1
was added triphenyl phosphine (5.0 g, 19.2 mmol), diethyl- obtained in 81% yield. R = 0.61 (10% MeOH/DCM). H NMR
f
azodicarboxylate (3.3 g, 19.2 mmol), diphenylphosphoryl azide (400 MHz, Chloroform-d) δ 7.46–7.10 (m, 5H), 4.93 (d, J =
(2.5 g, 9.6 mmol) sequentially. The reaction mixture was 3.7 Hz, 1H), 4.19 (q, J = 11.4 Hz, 1H), 4.07–3.94 (m, 3H), 3.84
stirred at room temperature for 24 h after which it was concen- (ddd, J = 12.3 Hz, 4.5 Hz, 1.9 Hz, 1H), 3.76 (d, J = 12.9 Hz, 1H),
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3
2
1
1
.54 (d, J = 12.9 Hz, 1H), 3.25 (td, J = 12.5 Hz, 1.8 Hz, 1H),
(3R,3aR,4S,7aS)-3-Methoxyhexahydro-2H-furo[2,3-b]pyran-
.72–2.65 (m, 1H) 2.32 (s, 3H), 1.81 (dd, J = 13.4 Hz, 5.6 Hz, 4-yl 4-nitrophenyl carbonate (27b). Following the general pro-
1
3
H), 1.68–1.52 (m, 1H). C NMR (100 MHz, CDCl
3
) δ 128.9, cedure outlined above, activated carbonate 27a was obtained in
1
28.6, 127.7, 100.6, 67.9, 62.8, 61.3, 60.3, 60.2, 43.5, 36.0, 30.5; 90% yield. R
f
= 0.29 (40% ethyl acetate/hexanes). H NMR
+
LRMS-ESI (m/z): 286.3 (M + Na) .
(300 MHz, Chloroform-d) δ 8.27 (d, J = 9.1 Hz, 2H), 7.38 (d, J =
(
3R,3aS,4S,7aS)-3-(Benzyl(ethyl)amino)hexahydro-2H-furo- 9.3 Hz, 2H), 5.22–4.97 (m, 2H), 4.36 (dd, J = 9.0 Hz, 6.8 Hz, 1H),
[
2,3-b]pyran-4-ol (25). Tertiary amine 25 was obtained follow- 4.27–4.22 (m, 1H), 4.07–3.84 (m, 2H), 3.51–3.34 (m, 1H), 3.34
13
ing the general procedure outlined above. Amine 25 was (s, 3H), 2.96–2.91 (m, 1H), 2.06–1.79 (m, 2H). C NMR (75 MHz,
D
obtained in 82% yield. R
f
= 0.34 (5% MeOH/DCM). [α]23
). H NMR (400 MHz, Chloroform-d) 72.6, 60.1, 58.0, 48.2, 26.9; LRMS-ESI (m/z): 362.4 (M + Na) .
δ 7.48–7.12 (m, 5H), 4.91 (d, J = 3.6 Hz, 1H), 4.16 (q, J = (3R,3aR,4S,7aS)-3-Ethoxyhexahydro-2H-furo[2,3-b]pyran-4-yl
1.3 Hz, 1H), 4.09–4.04 (m, 2H), 4.03–3.86 (m, 2H), 3.85–3.75 4-nitrophenyl carbonate (27c). Following the general proce-
m, 1H), 3.33 (d, J = 13.3 Hz, 1H), 3.23 (td, J = 12.4 Hz, 1.6 Hz, dure outlined above, activated carbonate 27c was obtained in
=
3
CDCl ) δ 155.5, 151.5, 145.4, 125.3, 121.7, 101.4, 79.2, 73.7,
1
+
+
74.6 (c 1.23, CHCl
3
1
(
1
1
H), 2.80 (dq, J = 14.7 Hz, 7.4 Hz, 1H), 2.66–2.63 (m, 1H), 2.43 48% yield. R = 0.17 (30% ethyl acetate/hexanes). H NMR
f
(
1
dq, J = 13.6 Hz, 6.9 Hz, 1H), 1.76 (dd, J = 13.3 Hz, 5.6 Hz, 1H), (400 MHz, Chloroform-d) δ 8.28 (m, J = 9.2 Hz, 2H), 7.40
.57–1.42 (m, 1H), 1.12 (t, J = 7.1 Hz, 3H). C NMR (100 MHz, (m, 2H), 5.24–5.15 (m, 1H), 5.14 (d, J = 3.8 Hz, 1H), 4.42–4.27
1
3
CDCl ) δ 137.7, 128.9, 128.6, 127.5, 100.4, 67.9, 64.1, 61.2, 57.9, (m, 2H), 4.01 (dt, J = 12.3 Hz, 3.7 Hz, 1H), 3.97–3.87 (m, 1H),
3
5
4.3, 44.1, 43.9, 30.6, 13.0.
3R,3aS,4S,7aS)-3-(Benzyl(propyl)amino)hexahydro-2H-furo- 2.03–1.90 (m, 2H), 1.15 (t, J = 7.0 Hz, 3H).
2,3-b]pyran-4-ol (26). Tertiary amine 26 was obtained follow- (3R,3aR,4S,7aS)-3-(Benzyloxy)hexahydro-2H-furo[2,3-b]pyran-
ing the general procedure outlined above. Amine 26 was 4-yl 4-nitrophenyl carbonate (27d). Following the general pro-
3.50 (q, J = 7.0 Hz, 2H), 3.45–3.33 (m, 1H), 2.98–2.95 (m, 1H),
(
[
1
f
obtained in 45% yield. R = 0.48 (5% MeOH/DCM). H NMR cedure outlined above, activated carbonate 27d was obtained
1
(400 MHz, Chloroform-d) δ 7.40–7.22 (m, 5H), 4.91 (d, J = in 87% yield. R = 0.35 (40% ethyl acetate/hexanes). H NMR
f
3
.6 Hz, 1H), 4.16 (q, J = 11.5 Hz, 1H), 4.08–4.01 (m, 2H), 3.98 (300 MHz, Chloroform-d) δ 8.11 (d, J = 7.1 Hz, 2H), 7.44–7.16
(d, J = 13.3 Hz, 1H), 3.94–3.87 (m, 1H), 3.81 (ddd, J = 12.2 Hz, (m, 5H), 7.04 (d, J = 7.1 Hz, 2H), 5.27–5.07 (m, 2H), 4.59–4.42
4
1
1
.4 Hz, 1.8 Hz, 1H), 3.33 (d, J = 13.3 Hz, 1H), 3.23 (td, J = (m, 3H), 4.33 (dd, J = 9.1 Hz, 6.9 Hz, 1H), 4.03–3.96 (m, 2H),
2.5 Hz, 1.8 Hz, 1H), 2.69–2.62 (m, 2H), 2.41–2.29 (m, 1H), 3.44–3.36 (m, 1H), 3.09–3.04 (m, 1H), 2.04–1.91 (m, 2H).
1
3
.75 (dd, J = 13.3 Hz, 5.6 Hz, 1H), 1.70–1.56 (m, 1H), 1.56–1.38
3
C NMR (75 MHz, CDCl ) δ 155.2, 151.5, 145.1, 137.4, 128.3,
1
3
(m, 2H), 0.87 (t, J = 7.4 Hz, 3H). C NMR (100 MHz, CDCl3) 127.9, 125.0, 121.6, 101.3, 77.3, 73.8, 72.9, 60.2, 48.3, 26.8;
+
δ 137.7, 129.0, 128.5, 127.5, 100.5, 67.9, 64.0, 61.2, 58.0, LRMS-ESI (m/z): 438.4 (M + Na) .
5
5.4, 51.8, 43.9, 30.5, 21.0, 11.5; LRMS-ESI (m/z): 314.5
(3R,3aS,4S,7aS)-3-Azidohexahydro-2H-furo[2,3-b]pyran-4-yl
4-nitrophenyl carbonate (27e). Following the general proce-
+
(M + Na) .
dure outlined above, activated carbonate 27e was obtained in
General procedure for the preparation of activated carbonates
from polycyclic P2-ligands
1
8
0% yield. R
f
= 0.25 (30% ethyl acetate/hexanes). H NMR
(
400 MHz, Chloroform-d) δ 8.28 (d, J = 9.2 Hz, 2H), 7.39 (d, J =
To a solution of the desired Tp-THF alcohol in dry CH Cl was 9.2 Hz, 2H), 5.29–5.22 (m, 1H), 5.15 (d, J = 3.6 Hz, 1H), 4.41
2 2
added pyridine (2.3 equivalents). The resulting mixture was (q, J = 8.0 Hz, 1H), 4.41–4.37 (m, 1H), 4.02 (dd, J = 12.5 Hz,
cooled to 0 °C under argon and 4-nitrophenylchloroformate 4.6 Hz, 1H), 3.87 (dd, J = 9.0 Hz, 4.9 Hz, 1H), 3.42 (td, J =
(
2.2 equivalents) was added in one portion. The resulting 12.2 Hz, 2.0 Hz, 1H), 2.88–2.79 (m, 1H), 2.15–2.01 (m, 1H),
1
3
3
mixture was stirred at 0 °C until completion. The reaction 1.95 (td, J = 12.1 Hz, 4.7 Hz, 1H). C NMR (100 MHz, CDCl )
mixture was evaporated to dryness and the residue was puri- δ 155.2, 151.6, 145.5, 125.3, 121.7, 101.7, 73.5, 72.5, 60.4, 59.3,
+
fied by flash column chromatography on silica gel using a gra- 48.9, 26.6; LRMS-ESI (m/z): 373.2 (M + Na) .
dient of 20–40% ethyl acetate/hexanes to afford the desired
mixed carbonate.
(3R,3aS,4S,7aS)-3-(Benzyl(methyl)amino)hexahydro-2H-furo-
[2,3-b]pyran-4-yl 4-nitrophen-yl carbonate (27f). Following the
(
3S,3aR,4S,7aS)-3-Methoxyhexahydro-2H-furo[2,3-b]pyran- general procedure outlined above, activated carbonate 27f was
-yl 4-nitrophenyl carbonate (27a). Following the general pro- obtained in 36% yield. R = 0.4 (40% ethyl acetate/hexanes).
H NMR (400 MHz, Chloroform-d) δ 8.20 (d, J = 9.2 Hz, 2H),
= 0.55 (60% ethyl acetate/hexanes). H NMR 7.34–7.09 (m, 7H), 5.25–5.07 (m, 2H), 4.10 (dd, J = 9.4 Hz,
400 MHz, Chloroform-d) δ 8.29 (d, J = 9.2 Hz, 2H), 7.39 (d, J = 4.4 Hz, 1H), 4.05–3.94 (m, 2H), 3.85 (td, J = 8.1 Hz, 4.4 Hz, 1H),
4
f
1
cedure outlined above, activated carbonate 27a was obtained
in 81% yield. R
(
1
f
9
4
.2 Hz, 2H), 5.26 (dt, J = 11.2 Hz, 6.3 Hz, 1H), 5.10 (d, J = 3.62 (d, J = 13.0 Hz, 1H), 3.50 (d, J = 13.1 Hz, 1H), 3.47–3.37
.0 Hz, 1H), 4.27 (dd, J = 9.7 Hz, 1.6 Hz, 1H), 4.15–4.08 (m, 1H), 3.11–3.06 (m, 1H), 2.21 (s, 3H),1.95 (dt, J = 8.6, 4.5 Hz,
1
3
(m, 1H), 4.05 (m, 1H), 3.50–3.41 (m, 2H), 3.40 (s, 3H), 2H). C NMR (100 MHz, CDCl
3
) δ 155.4, 151.7, 145.3, 138.4,
2
.58–2.54 (m, 1H), 2.39 (qd, J = 11.9 Hz, 4.8 Hz, 1H), 1.95–1.86 129.2, 128.2, 127.2, 125.2, 121.8, 101.3, 74.6, 64.9, 62.0, 60.3,
1
3
(m, 1H). C NMR (100 MHz, CDCl
3
) δ 155.4, 152.0, 145.4, 59.6, 43.9, 36.4, 26.7.
1
25.3, 121.7, 101.4, 80.1, 74.7, 74.6, 60.2, 58.5, 45.4, 28.2;
(3R,3aS,4S,7aS)-3-(Benzyl(ethyl)amino)hexahydro-2H-furo-
[2,3-b]pyran-4-yl 4-nitrophenyl carbonate (27g). Following
+
LRMS-ESI (m/z): 362.4 (M + Na) .
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the general procedure outlined above, activated carbonate 27g 1H), 2.55 (d, J = 4.5 Hz, 1H), 1.94–1.72 (m, 2H), 1.62 (dd, J =
was obtained in 77% yield. Rf = 0.6 (30% ethyl acetate/ 16.9 Hz, 7.9 Hz, 1H), 0.91 (d, J = 6.5 Hz, 3H), 0.86 (d, J =
1
hexanes). H NMR (400 MHz, Chloroform-d) δ 8.23 (d, J = 6.6 Hz, 3H). Mass: HRMS (ESI), Calcd for C30
H
42
N
2
O
9
S: m/z
9
3
.2 Hz, 2H), 7.32–7.14 (m, 7H), 5.24–5.19 (m, 1H), 5.17 (d, J = 629.2509 (M + Na), found m/z 629.2505 (M + Na).
.9 Hz, 1H), 4.08–3.98 (m, 2H), 3.97 (t, J = 3.6 Hz, 1H), 3.87 (3R,3aR,4S,7aS)-3-Methoxyhexahydro-2H-furo[2,3-b]pyran-
(d, J = 4.5 Hz, 1H), 3.75 (d, J = 13.7 Hz, 1H), 3.49–3.36 (m, 2H), 4-yl (2S,3R)-4-(4-amino-N-isobutylphenylsulfonamido)-3-hydroxy-
3
.03–2.98 (m, 1H), 2.62 (p, J = 7.2 Hz, 1H), 2.52–2.39 (p, J = 1-phenylbutan-2-ylcarbamate (30c). The titled inhibitor was
.8 Hz, 1H), 1.98–1.85 (m, 2H), 1.01 (t, J = 7.1 Hz, 3H). synthesized from amine 29 and activated carbonate 27b using
6
1
3
C NMR (100 MHz, CDCl
29.1, 128.1, 127.0, 125.2, 121.9, 101.1, 74.6, 66.1, 60.3, 59.1, obtained in 24% yield. H NMR (300 MHz, Chloroform-d)
3.1, 45.8, 44.5, 26.9, 12.5. δ 7.54 (d, J = 8.5 Hz, 2H), 7.41–7.00 (m, 5H), 6.67 (d, J = 8.6 Hz,
3R,3aS,4S,7aS)-3-(Benzyl(propyl)amino)hexahydro-2H-furo- 2H), 5.13 (d, J = 3.8 Hz, 1H), 5.03 (dd, J = 10.2 Hz, 5.2 Hz, 1H),
2,3-b]pyran-4-yl 4-nitrophenyl carbonate (27h). Following the 4.96 (d, J = 8.2 Hz, 1H), 4.39–3.99 (m, 3H), 3.99–3.70 (m, 6H),
general procedure outlined above, activated carbonate 27h was 3.48–3.24 (m, 2H), 3.12 (s, 3H), 3.02–2.83 (m, 4H), 2.75 (dd, J =
obtained in 32% yield. R = 0.6 (40% ethyl acetate/hexanes. 13.3 Hz, 6.3 Hz, 1H), 2.54 (d, J = 4.7 Hz, 1H), 1.89–1.64
H NMR (400 MHz, Chloroform-d) δ 8.23 (d, J = 9.2 Hz, 2H), (m, 3H), 0.91 (d, J = 6.5 Hz, 3H), 0.86 (d, J = 6.6 Hz, 3H). Mass:
3
) δ 155.4, 151.6, 145.3, 139.1, 131.0, the general procedure outlined above. Inhibitor 30c was
1
1
5
(
[
f
1
7
.32–7.13 (m, 7H), 5.23–5.18 (m, 1H), 5.17 (d, J = 3.9 Hz, 1H), LRMS: m/z 592.8 (M
+ H). Mass: HRMS (ESI), Calcd
4
.03 (d, J = 5.6 Hz, 2H), 4.01–3.95, (m, 1H), 3.85 (m, 1H), 3.76 for C29 S: m/z 614.2513 (M + Na), found m/z 614.2502
41 3 8
H N O
(d, J = 13.8 Hz, 1H), 3.48 (d, J = 13.8 Hz, 1H), 3.42 (td, J = 12.2 (M + Na).
Hz, 11.8 Hz, 3.3 Hz, 1H), 2.98–2.93 (m, 1H), 2.53–2.46 (m, 1H),
(3R,3aS,4S,7aS)-3-Hydroxyhexahydro-2H-furo[2,3-b]pyran-4-yl
2
1
.41–2.30 (m, 1H), 1.97–1.82 (m, 2H), 1.65–1.48 (m, 1H), (2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenyl-sulfonamido)-
.41–1.23 (m, 1H), 0.82 (t, J = 7.3 Hz, 3H). C NMR (100 MHz, 1-phenylbutan-2-ylcarbamate (30f). For the synthesis of inhibi-
1
3
CDCl ) δ 155.5, 151.7, 145.3, 139.2, 129.0, 128.2, 127.0, 125.3, tor 30f, compound 30e was treated with Pd(OH) (10 mol%) in
3
2
1
2
21.8, 101.3, 74.7, 66.6, 60.4, 59.4, 54.1, 52.6, 45.7, 26.9, methanol (2.0 mL) at 60 Psi for 12 h. The reaction was filtered
0.6, 11.7. through a plug of Celite and concentrated under vacuum. The
3S,3aR,4S,7aS)-3-Methoxyhexahydro-2H-furo[2,3-b]pyran- crude product was purified by silica gel chromatography to
-yl (2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenyl-sulfona- give the desired inhibitor 30f as an amorphous solid. (38%
(
4
1
mido)-1-phenylbutan-2-yl carbamate (30a). To a stirred solu- yield, 2 steps). R
f
= 0.22, (50% ethyl acetate/hexanes). H NMR
tion of amine 28 in CH CN at cooled to 0 °C, DIPEA (300 MHz, Chloroform-d) δ 7.72 (d, J = 7.1 Hz, 2H), 7.30–7.22
3
(5 equivalent) followed by activated ligand 27a. The resulting (m, 5H), 6.99 (d, J = 8.9 Hz, 2H), 5.17 (s, 1H), 5.04 (d, J =
solution was stirred at 23 °C until the reaction was complete. 3.7 Hz, 2H), 4.57 (s, 1H), 4.32 (t, J = 8.4 Hz, 1H), 3.88 (s, 7H),
The solution was evaporated to dryness and the crude residue 3.73 (dd, J = 9.2 Hz, 5.0 Hz, 1H), 3.41–3.08 (m, 2H), 3.02–2.90
purified by flash column chromatography on silica gel to yield (m, 4H), 2.79 (dd, J = 13.5 Hz, 6.8 Hz, 1H), 2.47 (s, 1H),
the desired inhibitor. The titled inhibitor was synthesized 1.93–1.52 (m, 3H), 0.88 (dd, J = 13.2 Hz, 6.4 Hz, 6H). Mass:
using the general procedure outlined above. The desired HRMS (ESI), Calcd for C H N O S: m/z 593.2532 (M + H) and
2
9
40 2 9
inhibitor was obtained as a white solid (15% yield). R
(
f
= 0.25 615.2352 (M + Na), found m/z 593.2520 (M + H) and 615.2330
60% ethyl acetate/hexanes). H NMR (400 MHz, Chloroform- (M + Na).
d) δ 7.72 (d, J = 8.8 Hz, 2H), 7.35–7.16 (m, 5H), 6.98 (d, J = (3R,3aR,4S,7aS)-3-Ethoxyhexahydro-2H-furo[2,3-b]pyran-4-yl
.9 Hz, 2H), 5.02–4.96 (m, 2H), 4.89 (d, J = 8.8 Hz, 1H), 4.16 (2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenyl-sulfonamido)-
1
8
(
(
d, J = 10.0 Hz, 1H), 4.03–3.92 (m, 3H), 3.92–3.84 (s, 4H), 3.78 1-phenylbutan-2-ylcarbamate (30d). The titled inhibitor 30d
bs, 1H), 3.46–3.27 (m, 3H), 3.19 (s, 3H), 3.16–3.08 (m, 1H), was synthesized using the general procedure outlined above.
3
f
.10–2.94 (m, 3H), 2.81 (dd, J = 13.4 Hz, 6.7 Hz, 2H), 2.31 Inhibitor 30d was obtained in 47% yield. R = 0.20 (40% ethyl
1
(d, J = 4.4 Hz, 1H), 2.18 (dd, J = 12.1 Hz, 4.4 Hz, 1H), 1.90–1.80 acetate/hexanes). H NMR (400 MHz, Chloroform-d) δ 7.69 (d,
m, 1H), 0.93 (d, J = 6.6 Hz, 3H), 0.87 (t, J = 7.6 Hz, 3H). Mass: J = 8.3 Hz, 2H), 7.41–7.12 (m, 5H), 6.97 (d, J = 8.9 Hz, 2H), 5.14
(
HRMS (ESI), Calcd for C30
found m/z 629.2505 (M + Na).
H
42
N
2
O
9
S: m/z 629.2509 (M + Na), (s, 1H), 5.04 (bs, 1H), 4.28–4.05 (m, 1H), 3.87 (s, 8H), 3.34 (d,
J = 7.0 Hz, 3H), 3.10–2.91 (d, 5H), 2.86–2.65 (m, 1H), 2.54 (bs,
(
3R,3aR,4S,7aS)-3-Methoxyhexahydro-2H-furo[2,3-b]pyran- 1H), 1.75–1.63 (m, 3H), 1.14–1.09 (m, 3H), 0.98–0.85 (m, 6H).
-yl (2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenyl-sulfona- Mass: LRMS: m/z 621.83 (M + H). Mass: HRMS (ESI), Calcd
mido)-1-phenylbutan-2-ylcarbamate (30b). The titled inhibitor for C31 S: m/z 643.2665 (M + Na), found m/z 643.2660
was synthesized using the general procedure outlined above. (M + Na).
Inhibitor 30b was obtained in 61% yield. R = 0.38 (60% ethyl (3R,3aR,4S,7aS)-3-(Benzyloxy)hexahydro-2H-furo[2,3-b]pyran-
4
44 2 9
H N O
f
1
acetate/hexanes). H NMR (300 MHz, Chloroform-d) δ 7.70 (d, 4-yl (2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxy-phenylsulfona-
J = 8.6 Hz, 2H), 7.43–7.13 (m, 5H), 6.97 (d, J = 8.7 Hz, 2H), 5.12 mido)-1-phenylbutan-2-ylcarbamate (30e). The titled inhibitor
(d, J = 3.7 Hz, 1H), 5.09–4.96 (m, 1H), 4.93 (d, J = 8.5 Hz, 1H), 30e was synthesized using the general procedure outlined
4
.17–4.12 (m, 1H), 3.87 (s, 9H), 3.47–3.25 (m, 1H), 3.12 (s, 3H), above. Inhibitor 30e was obtained in 82% yield. R
f
= 0.6, (50%
1
2
.96 (dd, J = 13.9 Hz, 7.4 Hz, 4H), 2.78 (dd, J = 13.3 Hz, 6.7 Hz, ethyl acetate/hexanes). H NMR (300 MHz, Chloroform-d) δ 7.69
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(d, J = 8.9 Hz, 2H), 7.39–7.10 (m, 10H), 6.96 (d, J = 8.9 Hz, 2H), The mixture was filtered through a plug of Celite and the fil-
5
8
3
2
.13 (d, J = 3.7 Hz, 1H), 5.05 (d, J = 4.3 Hz, 1H), 4.82 (d, J = trate was concentrated under reduced pressure. The residue
.4 Hz, 1H), 4.37 (s, 2H), 4.23–3.99 (m, 2H), 3.99–3.73 (m, 8H), was chromatographed on a silica gel column to provide inhibi-
.37 (t, J = 10.2 Hz, 1H), 3.09 (dd, J = 15.1 Hz, 8.4 Hz, 1H), tor 30i in 76% yield for two-steps. R
f
= 0.20 (10% methanol/
1
.95–2.95 (m, 4H), 2.78 (dd, J = 13.5 Hz, 6.7 Hz, 1H), 2.64–2.59 DCM). H NMR (400 MHz, CD OD) δ 7.77 (d, J = 8.9 Hz, 2H),
3
(m, 1H), 1.79 (d, J = 7.4 Hz, 2H), 1.71–1.53 (m, 1H), 0.88 (dd, 7.32–7.21 (m, 4H), 7.20–7.17 (m, 1H), 7.07 (d, J = 8.7 Hz, 2H),
J = 14.5 Hz, 7.0 Hz, 6H). Mass: LRMS: m/z 683.9 (M + H). Mass: 5.08 (d, J = 3.7 Hz, 1H), 5.00–4.91 (m, 1H), 4.21 (t, J =
HRMS (ESI), Calcd for C H N O S: m/z 705.2822 (M + Na), 8.4 Hz,1H), 3.87 (s, 3H), 3.86–3.65 (m, 4H), 3.50–3.34 (m, 3H),
3
6
46 2 9
found m/z 705.2816 (M + Na).
3R,3aS,4S,7aS)-3-Azidohexahydro-2H-furo[2,3-b]pyran-4-yl 1H), 2.95 (dd, J = 14.9 Hz, 8.1 Hz, 1H), 2.86 (dd, J = 13.6 Hz,
2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenyl-sulfonamido)- 6.9 Hz, 1H), 2.60 (dd, J = 14.0 Hz, 10.7 Hz, 1H), 2.38–2.26
-phenylbutan-2-ylcarbamate (30g). The titled inhibitor 30g (m, 2H), 2.24 (s, 3H), 2.10–1.92 (m, 1H), 1.85–1.74 (m, 1H),
was synthesized using the general procedure outlined above. 1.75–1.58 (m, 1H), 0.92 (d, J = 6.6 Hz, 3H), 0.87 (d, J = 6.6 Hz,
3.15 (dd, J = 14.0 Hz, 3.6 Hz, 1H), 3.06 (dd, J = 13.7 Hz, 8.2 Hz,
(
(
1
1
3
The desired inhibitor was obtained as an amorphous solid in 3H). C NMR (100 MHz, CDCl ) δ 164.5, 157.4, 140.2, 132.1,
3
1
7
5% yield. R
400 MHz, CD
.4 Hz, 4H), 7.19–7.15 (m, 1H), 7.11–7.01 (d, J = 8.8 Hz, 2H), HRMS (ESI), Calcd for C H N O S: m/z 606.2849 (M + H),
f
= 0.23 (40% ethyl acetate/hexanes). H NMR 130.6, 130.3, 129.2, 127.3, 115.4, 103.3, 74.2, 73.8, 70.5, 61.2,
(
3
OD) δ 7.75 (d, J = 8.8 Hz, 2H), 7.24 (d, J = 59.0, 58.9, 57.1, 56.2, 53.9, 36.6, 34.5, 28.5, 28.1, 20.5. Mass:
4
5
4
8
3
2
0
1
5
1
3
0
43 3 8
.09 (d, J = 3.7 Hz, 1H), 5.06–5.01 (m, 1H), 4.26–4.21 (m, 1H), found m/z 606.2840 (M + Na).
(3R,3aS,4S,7aS)-3-(Ethylamino)hexahydro-2H-furo[2,3-b]-
.9 Hz, 4.2 Hz, 1H), 3.39 (dd, J = 10.8 Hz, 4.1 Hz, 2H), pyran-4-yl
.12–3.00 (m, 3H), 2.90–2.85 (m, 1H), 2.72–2.60 (m, 1H), sulfonamido)-1-phenylbutan-2-ylcarbamate (30j). The titled
.48–2.41 (m, 1H), 2.04–1.97 (m, 1H), 1.83–1.62 (m, 2H), inhibitor was synthesized using the general procedure outlined
.97–0.80 (m, 6H). C NMR (100 MHz, CDCl ) δ 163.0, 155.4, above. The desired inhibitor 30j was obtained as an amor-
.23–4.14 (m, 1H), 3.86 (s, 4H), 3.81 (bs, 2H), 3.67 (dd, J =
(2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxy-phenyl-
1
3
3
37.4, 129.7, 129.4, 128.4, 126.6, 114.3, 99.3, 72.4, 72.3, 71.6, phous solid in 50% yield for the 2 steps. R
f
= 0.25 (10% metha-
OD) δ 7.76 (d, J = 8.8 Hz,
9.8. Mass: HRMS (ESI), calcd for (C H N O S): m/z 618.2598 2H), 7.36–7.13 (m, 5H), 7.13–7.02 (d, J = 9.2 Hz, 2H), 5.09
1
9.4, 58.7, 55.5, 55.3, 55.0, 53.5, 44.3, 35.3, 28.2, 27.2, 20.0, nol/DCM). H NMR (400 MHz, CD
3
2
9
39 5 8
(
M + H), found m/z 618.2597.
3R,3aS,4S,7aS)-3-Aminohexahydro-2H-furo[2,3-b]pyran-4-yl 4.25–4.14 (t, J = 8.8 Hz, 1H), 3.87 (s, 3H), 3.86–3.79 (m, 3H),
2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenyl-sulfonamido)- 3.78–3.72 (m, 1H), 3.70 (dd, J = 8.7 Hz, 5.1 Hz, 1H), 3.50 (td, J =
-phenylbutan-2-ylcarbamate (30h). Inhibitor 30g was dis- 7.3 Hz, 5.3 Hz, 1H), 3.46–3.35 (m, 2H), 3.15 (dd, J = 14.0 Hz,
(d, J = 3.8 Hz, 1H), 5.01 (dq, J = 10.7 Hz, 5.3 Hz, 4.7 Hz, 1H),
(
(
1
solved in ethyl acetate and 10% Pd/C (10% by weight) was 3.7 Hz, 1H), 3.05 (dd, J = 13.6 Hz, 8.1 Hz, 1H), 2.96 (dd, J =
added. The resulting mixture was stirred under a hydrogen- 14.9 Hz, 8.3 Hz, 1H), 2.87 (dd, J = 13.6 Hz, 6.9 Hz, 1H),
filled balloon for 1 h. The mixture was filtered through a plug 2.65–2.51 (m, 2H), 2.50–2.41 (m, 1H), 2.29 (td, J = 6.8 Hz,
of Celite and concentrated under vacuum. The crude product 4.0 Hz, 1H), 2.07–1.96 (m, 1H), 1.82–1.60 (m, 2H), 1.10 (t, J =
was purified by silica gel chromatography to obtain inhibitor 7.1 Hz, 3H), 0.91 (d, J = 6.6 Hz, 3H), 0.86 (d, J = 6.6 Hz, 3H).
1
3
3
NH
0h as an amorphous solid in 85% yield. R
f
= 0.18 (5% (5%
3
C NMR (100 MHz, CD OD) δ 164.5, 157.4, 140.2, 132.2,
1
3
/MeOH)/dichloromethane). H NMR (400 MHz, Chloro- 130.6, 130.3, 129.3, 127.3, 115.4, 103.1, 74.3, 74.1, 70.4, 60.9,
form-d) δ 7.71 (d, J = 8.8 Hz, 2H), 7.37–7.14 (m, 5H), 6.97 (d, J = 58.8, 57.4, 57.2, 56.2, 53.9, 43.5, 36.7, 28.6, 28.1, 20.5, 15.0.
8
9
4
1
1
6
.7 Hz, 2H), 5.53 (s, 1H), 5.34–5.13 (m, 2H), 4.07 (dd, J = Mass: HRMS (ESI), Calcd for C31
.8 Hz, 7.0 Hz, 1H), 3.98–3.73 (m, 8H), 3.67 (dd, J = 9.6 Hz, (M + Na), found m/z 620.3000 (M + Na).
.9 Hz, 1H), 3.36–3.27 (m, 1H), 3.17 (dd, J = 14.9 Hz, 8.9 Hz, (3R,3aS,4S,7aS)-3-(Ethylamino)hexahydro-2H-furo[2,3-b]-
H), 3.04–2.68 (m, 5H), 2.66–2.16 (bs, 2H), 2.10–1.95 (m, 1H), pyran-4-yl (2S,3R)-4-(4-amino-N-isobutylphenyl-sulfonamido)-
.82 (dd, J = 14.1, 6.9 Hz, 2H), 1.46–1.28 (m, 1H), 0.89 (d, J = 3-hydroxy-1-phenylbutan-2-ylcarbamate (30k). The titled
.5 Hz, 3H), 0.85 (d, J = 6.5 Hz, 3H). Mass: LRMS: m/z 592.8 inhibitor 30k was synthesized following the general procedure
45 3 8
H N O S: m/z 620.3005
(
5
M + H). Mass: HRMS (ESI), Calcd for C29
92.2693 (M + H), found m/z 592.2686 (M + H).
H
41
N
3
O
8
S: m/z outlined above. The desired inhibitor was obtained as an
1
amorphous solid in 61% yield for the 2 steps. H NMR
(
3R,3aS,4S,7aS)-3-(Methylamino)hexahydro-2H-furo[2,3-b]- (400 MHz, CD OD) δ 7.47 (d, J = 8.8 Hz, 2H), 7.32–7.10
3
pyran-4-yl
(2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxy-phenyl- (m, 5H), 6.68 (d, J = 9.1 Hz, 2H), 5.09 (d, J = 3.7 Hz, 1H),
sulfonamido)-1-phenylbutan-2-yl carbamate (30i). To a stirred 5.04–4.92 (m, 2H), 4.21 (t, J = 8.0 Hz, 1H), 3.95–3.79 (m, 2H),
solution of amine 28 and activated carbonate 27f in CH CN, 3.90–3.79 (m, 2H), 3.53–3.48 (m,1H), 3.44–3.33 (m, 3H), 3.17
3
DIPEA (5 equivalent) was added and the resulting mixture was (dd, J = 14.0 Hz, 3.7 Hz, 2H), 2.99 (dd, J = 13.6 Hz, 8.2 Hz, 1H),
stirred for 24 h. Standard work up and purification as 2.89 (dd, J = 14.8 Hz, 8.4 Hz, 1H), 2.80 (dd, J = 13.5 Hz, 6.8 Hz,
described for inhibitor 30a provided the corresponding carba- 1H), 2.65–2.51 (m, 2H), 2.50–2.43 (m, 1H), 2.31–2.26 (m, 1H),
mate derivative. Above carbamate was dissolved in 5% 2.03–1.98 (m, 1H), 1.78–1.63 (d, 2H), 1.10 (t, J = 7.1 Hz, 3H),
ammonia in MeOH (2 mL) and 10% Pd(OH)
2
was added. The 0.92 (d, J = 6.5 Hz, 3H), 0.89–0.80 (d, J = 6.5 Hz, 3H). Mass:
mixture was stirred under a hydrogen-filled balloon for 4 h. LRMS: m/z 605.8 (M + H). Mass: HRMS (ESI), Calcd for
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3
7
30 44 4 7
C H N O S: m/z 605.3009 (M + H), found m/z 605.3005 refined by SHELX-97 to 1.22 Å and 1.62 Å resolution, respect-
3
8
(
M + H).
3R,3aS,4S,7aS)-3-(Propylamino)hexahydro-2H-furo[2,3-b]- tures. PRODRG-2 was used to construct the inhibitor and the
pyran-4-yl (2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenyl- restraints for refinement. Alternative conformations were
ively. COOT was used for visual modification of the struc-
3
9
(
sulfonamido)-1-phenylbutan-2-ylcarbamate (30l). The titled modeled. Anisotropic atomic displacement parameters
inhibitor 30l was synthesized following the general procedure (B factors) were applied for all atoms, including solvent mole-
outlined above. Inhibitor 30l was obtained as an amorphous cules in the higher resolution complex of HIV protease with
1
solid in 60% yield. H NMR (400 MHz, CD OD) δ 7.76 (d, J = inhibitor 30b. The final refined solvent structure comprised
3
8
.9 Hz, 2H), 7.35–7.14 (m, 5H), 7.08 (d, J = 8.9 Hz, 2H), 5.10 two sodium ions, three chloride ions, one acetate ion and 186
d, J = 3.8 Hz, 1H), 5.04–4.99 (m, 1H), 4.21 (t, J = 6.8 Hz, 1H), water molecules for HIV protease with inhibitor 30b and one
.88 (s, 4H), 3.86–3.79 (m, 1H), 3.79–3.68 (m, 2H), 3.53–3.48 sodium ion, three chloride ions and 138 water molecules for
m, 1H), 3.47–3.35 (m, 3H), 3.26–3.24 (m, 1H), 3.18–3.11 (dd, HIV protease with inhibitor 30j. The crystallographic statistics
J = 14.0 Hz, 3.6 Hz, 1H), 3.05 (dd, J = 13.4 Hz, 8.4 Hz, 1H), 2.96 are listed in Table 2 (ESI†). The coordinates and structure
dd, J = 14.9 Hz, 8.3 Hz, 1H), 2.86 (dd, J = 14.9 Hz, 8.3 Hz, 1H), factors of the HIV-1 protease complexes with inhibitor 30b and
(
3
(
(
2.62 (dd, J = 14.0 Hz, 10.7 Hz, 1H), 2.55–2.45 (m, 1H), inhibitor 30j have been deposited in the Protein Data Bank
2.45–2.35 (m, 1H), 2.34–2.30 (m, 1H), 2.07–1.94 (m, 1H), with accession codes 5DGU and 5DGW.
1.83–1.62 (m, 2H), 1.55–1.45 (m, 1H), 0.97–0.89 (m, 6H), 0.86
(
d, J = 6.7 Hz, 3H). Mass: LRMS: m/z 634. 9 (M + H). Mass:
HRMS (ESI), Calcd for C32 S: m/z 634.3163 (M + H),
found m/z 634.3156 (M + H).
3R,3aS,4S,7aS)-3-(Dimethylamino)hexahydro-2H-furo[2,3-b]- This research was supported by the National Institutes of
pyran-4-yl (2S,3R)-3-hydroxy-4-(N-isobutyl-4-methoxyphenylsul- Health (Grant GM53386, AKG and Grant GM62920, ITW). X-ray
fonamido)-1-phenylbutan-2-ylcarbamate (30m). Compound data were collected at the Southeast Regional Collaborative
0h was dissolved in 1,2-dichloroethane (2 mL). Powdered Access Team (SER-CAT) beamline 22BM at the Advanced
47 3 8
H N O
Acknowledgements
(
3
paraformaldehyde (3 equivalent) and sodium triacetoxy boro- Photon Source, Argonne National Laboratory. Use of the
hydride (3 equivalent) were added and the mixture was stirred Advanced Photon Source was supported by the US Department
for 24 h. The crude inhibitor was purified by silca gel chrom- of Energy, Basic Energy Sciences, Office of Science, under
atography to obtain the desired inhibitor 30m as an amor- Contract No. W-31-109-Eng-38. This work was also supported
phous solid in 67% yield. R = 0.25 (10% methanol/DCM). by the Intramural Research Program of the Center for Cancer
f
1
3
H NMR (400 MHz, CD OD) δ 7.77 (d, J = 8.8 Hz, 2H), Research, National Cancer Institute, National Institutes of
7.29–7.18 (m, 5H), 7.08 (d, J = 8.8 Hz, 2H), 5.18 (d, J = 4.3 Hz, Health, and in part by a Grant-in-Aid for Scientific Research
1H), 5.01–4.98 (m, 1H), 4.18–4.01 (m, 1H), 3.96–3.83 (m, 5H), (Priority Areas) from the Ministry of Education, Culture,
3.84–3.76 (m, 2H), 3.50–3.42 (m, 3H), 3.15 (dd, J = 13.8 Hz, Sports, Science, and Technology of Japan (Monbu Kagakusho),
2.5 Hz, 1H), 3.06 (dd, J = 13.7 Hz, 8.1 Hz, 1H), 2.96 (dd, J = a Grant for Promotion of AIDS Research from the Ministry of
14.8 Hz, 7.8 Hz, 1H), 2.87 (dd, J = 13.6 Hz, 6.9 Hz, 1H), Health, Welfare, and Labor of Japan, and the Grant to the
2.67–2.50 (m, 1H), 2.23 (s, 3H), 1.97 (s, 3H), 1.81–1.71 (m, 1H), Cooperative Research Project on Clinical and Epidemiological
1.70–1.61 (m, 1H), 0.92 (d, J = 6.6 Hz, 3H), 0.87 (d, J = 6.6 Hz, Studies of Emerging and Reemerging Infectious Diseases
3H). Mass: LRMS: m/z 620.8 (M + H). Mass: HRMS (ESI), Calcd (Renkei Jigyo) of Monbu-Kagakusho. The authors would like to
for C31
H
45
N
3
O
8
S: m/z 620.3006 (M + H), found m/z 620.2998 thank the Purdue University Center for Cancer Research, which
supports the shared NMR and mass spectrometry facilities. The
(M + H).
authors would also like to thank Mr. Steve Scherer (Purdue Uni-
versity) for his help with the cover page.
Methods: determination of X-ray structures of HIV-1
protease–inhibitor complexes
The optimized HIV-1 protease was expressed and purified as
3
1
described. The protease–inhibitor complex was crystallized
by the hanging drop vapor diffusion method with well solu-
tions of 1.18 M NaCl, 0.1 M sodium acetate buffer (pH 4.6) for
the complex with inhibitor 30b and 1.3 M NaCl, 0.1 M sodium
acetate buffer (pH 5.5) for the complex with inhibitor 30j
respectively. X-ray diffraction data were collected on a single
crystal cooling to 90 K at SER-CAT (22-BM beamline), Advanced
Photon Source, Argonne National Lab (Chicago, USA) with
Notes and references
1 A. Edmonds, M. Yotebieng, J. Lusiama, Y. Matumona,
F. Kitetele, S. Napravnik, S. R. Cole, A. Van Rie and
F. Behets, PLoS Med., 2011, 8, e1001044.
2 H. Mitsuya, K. Maeda, D. Das and A. K. Ghosh, Adv. Phar-
macol., 2008, 56, 169–197.
3 S. Hue, R. J. Gifford, D. Dunn, E. Fernhill and D. Pillay,
J. Virol., 2009, 83, 2645–2654.
3
2
X-ray wavelength of 1.0 Å, and processed by HKL-2000 with
an Rmerge of 6.8% and 5.7%, respectively, for the 30b and 30j
4 B. Conway, Future Virol., 2009, 4, 39–41.
5 A. K. Ghosh, D. D. Anderson, I. T. Weber and H. Mitsuya,
Angew. Chem., Int. Ed., 2012, 51, 1778–1802.
3
3
complexes. Using the isomorphous structure, the crystal
3
4
35,36
structures were solved by PHASER in CCP4i Suite
and
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6
7
A. K. Ghosh, B. D. Chapsal, I. T. Weber and H. Mitsuya,
Acc. Chem. Res., 2008, 41, 78–86.
A. K. Ghosh, B. Chapsal and H. Mitsuya, in Aspartic Acid 24 K. C. Kumara Swamy, N. N. Bhuvan Kumar, E. Balaraman
I. T. Weber and H. Mitsuya, J. Med. Chem., 2013, 56, 6792–
6802.
Proteases as Therapeutic Targets, ed. A. K. Ghosh, Wiley-VCH
Verlag GmbH & Co. KGaA, Weinheim, 2010, pp. 205–243.
and K. V. P. Pavan Kumar, Chem. Rev., 2009, 109, 2551–
2651.
8
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