Is adamantane a suitable substituent to pre-organize the acid orientation in E-selectin antagonists?

Article abstract of DOI:10.1016/j.bmc.2007.07.025

The selectins play a key role in the inflammatory process, that is, the recruitment of leukocytes from blood vessels into inflamed tissue. Because excessive infiltration of leukocytes can induce acute or chronic reactions, the control of leukocyte extrava

Full text of DOI:10.1016/j.bmc.2007.07.025

Bioorganic & Medicinal Chemistry 16 (2008) 1046–1056
Is adamantane a suitable substituent to pre-organize
the acid orientation in E-selectin antagonists?
a
b
c
a
a
´
Alexander Titz, John Patton, Andre M. Alker, Michele Porro, Oliver Schwardt,
Michael Hennig,c Eric Francotte,d John Magnanib and Beat Ernsta,*
aInstitute of Molecular Pharmacy, University of Basel, CH-4056 Basel, Switzerland
bGlycoMimetics Inc., Gaithersburg, MD 20878, USA
cF. Hoffmann-La Roche Ltd, X-ray Crystallography 65/310, CH-4070 Basel, Switzerland
dNovartis Institutes for BioMedical Research, CH-4002 Basel, Switzerland
Received 19 February 2007; revised 1 July 2007; accepted 10 July 2007
Available online 22 August 2007
Abstract—The selectins play a key role in the inflammatory process, that is, the recruitment of leukocytes from blood vessels
into inflamed tissue. Because excessive infiltration of leukocytes can induce acute or chronic reactions, the control of leuko-
cyte extravasation is of great pharmaceutical interest. All physiological ligands of the selectins contain the tetrasaccharide epi-
tope sialyl Lewisx, which therefore became the lead structure in selectin antagonist research. Previous studies indicated that an
important factor for the affinity of sLex is the fact that in solution its pharmacophores are already conformationally pre-orga-
nized in the bioactive orientation. In mimics where the GlcNAc- and the NeuNAc-moieties of sLex were replaced by (R,R)-
cyclohexane-1,2-diol and (S)-cyclohexyllactic acid, respectively, an optimized pre-organization of the pharmacophores could be
realized, leading to antagonists with improved affinities. To further optimize the pre-organization of the carboxylic acid, a
pharmacophore essential for binding, the replacement of NeuNAc by bulky (R)- and (S)-adamantyl-lactic acid was studied.
Although antagonist (S)-7 showed a slightly reduced affinity, the expected beneficial effect of the (S)-configuration at C-2 of
the lactate could be confirmed.
ꢀ 2007 Elsevier Ltd. All rights reserved.
1. Introduction
stroke or rheumatoid arthritis.7 Therefore, the antago-
nism of selectins is regarded as a valuable pharmaceuti-
cal goal.
The selectins play a key role in the body’s defense mech-
anism against inflammation.1 They form a class of three
cell adhesion molecules (E-, P-, and L-selectin), which,
in case of an inflammatory stimulus, are responsible
for the initial steps of the inflammatory response, that
is, the tethering and rolling of leukocytes on endothelial
cells. As shown with anti-selectin antibodies2–4 and E-,
P-, and L-selectin k.o. mice,5,6 these early steps are a
prerequisite for the inflammatory cascade to take place.
The following steps, that is, firm adhesion and finally
extravasation of leukocytes into the adjacent inflamed
tissue, do not take place when the initial rolling is pre-
vented. On the other hand, excessive infiltration of leu-
kocytes into the adjacent tissue can lead to acute or
chronic reactions, as observed in reperfusion injuries,
Since all physiological ligands of the selectins contain
the sialyl Lewisx motif (sLex, 1, Fig. 1),8 this tetrasac-
charide, although it exhibits only a moderate affinity
(IC50 = 1 mM), was chosen as lead structure in the
search for E-selectin antagonists. The solution9 and
the bioactive10,11 conformation of sLex are known,
and its pharmacophores have been identified.12–15
We have shown that the pre-organization of the phar-
macophores in the bioactive conformation contributes
substantially to the affinity of E-selectin antagonists.16,17
To describe the degree of pre-organization of E-selectin
antagonists, two internal dihedral angles have been de-
fined (Fig. 2): (i) the core conformation depicting the rel-
ative orientation of L-fucose and D-galactose and (ii) the
acid orientation indicating the tilting angle of the car-
boxylic acid toward the D-Gal(b1–4)[L-Fuc(a1–3)]D-
GlcNAc core. By a Monte-Carlo (jumping between
Keywords: E-selectin; Sialyl Lewisx; Pre-organization; Adamantane.
*
Corresponding author. Tel.: +41 61 267 1550; fax: +41 61 267
1552; e-mail: beat.ernst@unibas.ch
0968-0896/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2007.07.025

A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
1047
HO
OH
AcHN
HO
OH
O
OH
OH
HOOC
O
O
O
O
HO
HO
O
OR
NHAc
Me
O
OH
OH
HO
1
Figure 1. The natural tetrasaccharide epitope sialyl Lewisx (1, sLex, essential pharmacophores for binding to E-selectin are highlighted in boldface)
and its bioactive conformation as determined by trNOE NMR.10,11
OH
O
AcHN
OH
HO
Me
OH
O
OH
O
HO
OH
O
O
O
NaOOC
O
O
O
NaOOC
O
O
O
O
HO2C
HO
HO
O
HO
O
HO
O
OH
OH
OH
OH
HO
OH
HO
OH
OH
OH
HO
220, IC50 = 0.6 mM
3, rIC50 > 10
(S)-4, rIC50 = 2.4
(R)-4, rIC50 > 10
rIC50 = 1
OH
OH
O
NaOOC
O
HO
NaOOC
O
O
O
O
O
O
HO
O
O
OH
OH
OH
HO
OH
HO
OH
OH
(S)-520, rIC50 = 0.6
(R)-520, rIC50 > 10
(S)-6, rIC50 = 0.15
(R)-6, rIC50 > 10
Figure 2. Mimics 3–6 of the sLex derivative 2 indicate the influence of the acid orientation for affinity.16 The affinities are given as rel. affinities, that
is, relative to mimic 2 which has an IC50 of 0.6 mM and rIC50 = 1. Core conformation (=relative orientation of L-fucose and D-galactose, indicated in
red) and acid orientation (=tilting angle of the carboxylic acid relative to the core, indicated in blue) are shown in 2.
wells)/stochastic dynamics (MC(JBW)/SD) protocol,
affinities of selectin antagonists could be predicted as a
function of their pre-organization with respect to core/
acid orientation.16
(R,R)-cyclohexane-1,2-diol (!2,20 Fig. 2), resulted in
equal or even improved affinities.16,19–21
Although the importance of the pre-organization of the
acid orientation for the affinity of selectin antagonists
has been demonstrated,16 only a few studies to further
stabilize the acid orientation in the bioactive conforma-
tion have been reported. Since only the carboxylic acid
of D-NeuNAc acts as a pharmacophore, the sugar moi-
ety was replaced by non-carbohydrate acids. The first at-
tempt using glycolic acid showed a substantial reduction
in affinity due to reduced pre-organization of the car-
boxylic acid function (3, Fig. 2).16 However, when D-
NeuNAc was replaced by (S)-lactic acid (!(S)-4) and
lactic acid derivatives (!(S)-520 or (S)-6), affinity was
From the crystal structure of all three selectins co-crys-
tallized with sLex (1),18 it is known that the D-GlcNAc
residue solely serves as a linker to orient the D-Gal-
and the L-Fuc-moiety in the correct spatial orientation
and does not contribute to the binding enthalpy. This
is in agreement with the observation that the replace-
ment of the D-GlcNAc moiety by flexible 1,2-diols16–19
leads to a tremendous loss in affinity as a consequence
of the loss in pre-organization. On the other hand, D-
GlcNAc replacements by rigid linkers, for example,

1048
A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
regained. The corresponding diastereomers (R)-4 to (R)-
6, however, showed no affinity. A careful analysis of
R- and S-isomers by MC(JBW)/SD simulations clearly
indicated that the S-isomers are pre-organized in the
bioactive conformation, whereas the R-isomers are
not. For binding to E-selectin, the R-isomers have there-
fore to undergo a conformational change accompanied
by substantial entropy costs.16 In addition to the
observed configurational prerequisite, the affinity also
depends on the lipophilicity or the bulkiness of the lactic
acid substituent, that is, going from glycolate, to lactate,
2-phenyl lactate, and 2-cyclohexyl lactate an increase in
affinity could be observed.
of 7, however, shows a conformational focus point out-
side the bioactive area (Fig. 3a). Since (S)-7 shows a
higher degree of pre-organization than (S)-6, the most
active compound in Figure 2, an improved affinity was
expected.
The retrosynthetic analysis for the two diasteromeric
adamantyl derivatives (R)/(S)-7 (Scheme 1) generated
the adamantyl-lactic acid derivatives (R)/(S)-8 and the
known building blocks 924 and 10.19
Racemic adamantyl-lactic acid (rac-12, Scheme 2) was
obtained by a Giese-type radical addition of the ada-
mantyl radical generated from 1-adamantyl bromide to
the acrylate 11, followed by hydrolysis of the ethyl es-
ter.25 Subsequent formation of the benzyl ester (!rac-
13) followed by preparative chiral resolution on a Chir-
alpak AD-H column yielded the two enantiomers (S)-13
(ee 99.5%) and (R)-13 (ee 99.6%). The chiral resolution
with the corresponding methyl and p-nitrobenzyl deriv-
atives was less efficient, because the differences in reten-
tion time for the two enantiomers were smaller than in
case of the benzyl ester rac-13. By transforming the
enantiomers (S)-13 and (R)-13 into the corresponding
triflates (S)-14 and (R)-14, the electrophiles needed for
the alkylation of the 3-position of the galactose moiety
were obtained.
From the docking studies22 of the lowest energy confor-
mation of a Monte-Carlo search of (S)-6 to E-selectin
using the Yeti program,23 it becomes evident that the
cyclohexyl group is not establishing an additional lipo-
philic contact with the binding site of the lectin. There-
fore, it was assumed that the increase in activity
originates predominantly from an increased degree of
pre-organization. To further verify the influence of the
lipophilicity/bulkiness of the lactic acid substituent, the
corresponding adamantyl derivatives (R)-7 and (S)-7
were analyzed by molecular modeling, synthesized,
and biologically evaluated.
2. Results and discussion
For the assignment of the absolute configuration of the
adamantyl building blocks, racemic adamantyl-lactic
acid (rac-12) was treated with the chiral auxiliary (S)-a
methylbenzylamine (15)26 to yield the two correspond-
ing diastereomeric amides 16 and 17 (Scheme 3). Since
the two diastereomers exhibit significantly different Rf
values, they could be separated by standard column
chromatography on silica gel. Because diastereomer 16
The analysis of the two diastereomeric adamantyl deriv-
atives (R)-7 and (S)-7 (Fig. 3) was conducted according
to the MC(JBW)/SD protocol.16 The S-isomer shows a
high degree of pre-organization in the area of the bioac-
tive window (indicated in the core conformation/acid
orientation plot by a red square, Fig. 3b). The R-isomer
b
a
OH
OH
NaOOC
O
O
NaOOC
O
O
O
O
O
O
HO
O
HO
O
OH
OH
HO
OH
OH
HO
OH
OH
(S)-7
(R)-7
Probability code
core conformation
core conformation
Figure 3. Core conformation/acid orientation plot of both adamantyl bearing E-selectin antagonist (R)-7 and (S)-7. The bioactive window is
indicated with a red square.

A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
1049
OBz
O
BzO
BzO
SEt
O
OTf
OBn
OBn
OH
O
O
O
(R)/(S)-8
9
O
O
ONa
HO
O
OH
OH
HO
O
OH
HO
O
(R)/(S)-7
OBn
OBn
BnO
10
Scheme 1. Retrosynthetic analysis for the target compounds.
O
OBn
OH
O
OBn
OTf
(viii)
O
OH
OH
(S)-13
(S)-14
O
O
(i)
(ii)-(iv)
(v) - (vii)
O
OTMS
EtO
EtO
O
OBn
OH
O
OBn
OTf
11
rac-12
(viii)
(R)-13
(R)-14
Scheme 2. Reagents and conditions: synthesis of the adamantyl-lactic acids. (i) TMSCl, TEA, Et2O, 0 ꢁC–rt, 3.5 h (85%); (ii) Bu3SnH, AIBN, 1-
adamantyl bromide, PhMe, reflux, 14 h; (iii) KF, H2O, rt, overnight; (iv) NaOH, H2O, 50 ꢁC, 12 h; HCl (54% for three steps); (v) Cs2CO3, MeOH,
H2O; (vi) BnBr, DMF, rt, 20 h (73% for two steps); (vii) chiral resolution, HPLC Chiralpak AD-H ((S)-13: ee 99.5%; (R)-13: ee 99.6%); (viii) Tf2O,
DCM, 2,6-tBu2–py, 0–20 ꢁC, 3 h ((S)-14: 96%; (R)-14 79%).
could be crystallized, the determination of its absolute
configuration by X-ray crystallography was possible
(Table 1 and Fig. 4). It is noteworthy that the asymmet-
ric unit contains three molecules of which two have a
stretched and one a collapsed conformation (Fig. 4). Be-
cause (R)-13 could be transformed into 17, the alloca-
tion of the absolute configuration of the adamantyl
derivatives (S)-13 and (R)-13 was achieved.
For the desired antagonist (S)-7, the regioselective
alkylation of the 3-position of the galactose moiety
was achieved using the alkylating agent (R)-14 and
the mild tin-acetal coupling procedure.29 Due to the in-
creased steric bulk of the adamantyl substituent, the
yield (21%) was rather low. In addition, a significant
amount of a side product, benzyl (S)-3-(1-adamantyl)-
2-fluoro-propionate (23, see experimental part for de-
tails), was isolated. The formation of 23 is a conse-
quence of the bulkiness of the adamantyl substituent,
allowing the stannophilic fluoride ion, which is used
to open the stannylene acetal regioselectively, to act
also as nucleophile. The sodium salt of the acid (S)-7
was obtained after hydrogenolysis and ion exchange
chromatography. Finally, possible traces of the polyan-
ionic ion exchange resin, which would lead to false po-
sitive results,30 were removed by size exclusion
chromatography.
The synthesis of the selectin antagonists 7 started from
(R,R)-cyclohexane-1,2-diol (19) which was a-fucosylat-
ed with the thiofucoside donor 1817 according to the
in situ anomerization procedure developed by Lemi-
eux27 (Scheme 4). In a second glycosylation step, 10
was galactosylated with thiogalactoside donor 9 using
DMTST28 as promotor. Finally, removal of the benzo-
ate protective groups by transesterification yielded the
core molecule 21.21

1050
A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
in case of (R)-14). After hydrogenolysis, the crude prod-
uct was treated with aqueous sodium hydroxide to open
the d-lactone. Diastereomer (R)-7 was finally obtained
after size exclusion chromatography.
O
NH
OH
O
OH
OH
The results obtained in a competitive binding assay31 con-
firmed our prediction that the S-configurated lactic acid
substituent leads to active antagonists, whereas the R-
configuration produces inactive compounds. However,
contrary to the predicted properties, (S)-7 (rIC50 = 0.32)
is slightly less active than (S)-6 (rIC50 = 0.15).
(i)
+
NH2
16
15
rac-12
3. Conclusion
O
NH
OH
O
OBn
OH
Docking studies using the crystal structure of E-selectin
and a bioactive conformation of (S)-7, which was
extrapolated from the one of 1,11 clearly demonstrated
that no interaction of the adamantyl substituent with
the protein occurs. Thus, the bulky adamantyl substitu-
ent solely contributes to the stabilization of the acid ori-
entation. Since the predicted acid orientation in (S)-7
(Fig. 3) is superior to the one in (S)-6,16 lower entropy
costs upon binding, and therefore an improved affinity
to E-selectin was expected. One possible explanation
for the discrepancy between our prediction based on
molecular modeling and the test results may be related
to the lipophilicity of the adamantyl substituent, which
could lead to aggregate formation or unfavorable solva-
tion properties.
(ii)
(R)-13
17
Scheme 3. Reagents and conditions: determination of the absolute
configuration of the adamantyl derivatives (S)-13 and (R)-13: (i)
dioxane, lW, 180 ꢁC, 15 min (85%); (ii) 15, dioxane, 80 ꢁC, 48 h
(quant.).
Table 1. Crystallographic data of amide 16
Compound
16
626224
CCDC number
Empirical formula
Formula weight
Temperature (K)
4. Experimental
C21H29NO2
327.45
100
4.1. General methods
˚
Wavelength (A)
1.54184
Orthorhombic
P212121
Crystal system
Space group
Cell dimensions
Analyses of the conformational preferences of the E-
selectin antagonists were performed in aqueous solution
by applying the systematic pseudo-Monte-Carlo (MC)
(SUMM, systematic multiple minimum search) simula-
tion technique32 and the ‘Jumping Between Wells/Sto-
chastic Dynamics’ ((JBW)/SD) protocol16 implemented
in MacroModel 5.0.33 First, the locations of the most
relevant energy minima (conformations) of a compound
were determined in an internal coordinate systematic
pseudo-Monte-Carlo SUMM simulation.32 2000 steps
were performed for each free-rotatable bond excluding
terminal CH3 groups. All structures within 20 kJ/mol
from the energy of the global minimum were retained.
The shape of the potential energy surface was then
probed in a subsequent JBW/SD simulation, which used
the information obtained in the SUMM analysis. Thus,
a Boltzmann-weighted ensemble of states was generated
in a 10 ns MC(JBW)/SD simulation by jumping between
different energy wells, that is, the energetically best 100
conformations found in the preceeding SUMM analysis,
and performing stochastic dynamics simulations within
each well. All calculations were performed using the
AMBER34 force field augmented by parameters for car-
bohydrates16,35 and in conjunction with the GB/SA con-
tinuum water model for implicit solvation.36 This led to
a realistic sampling of the conformational space of the
structure of interest.
˚
a (A)
10.386(2)
18.795(4)
˚
b (A)
˚
c (A)
28.311(6)
90
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
3
˚
Volume (A )
5526.1(19)
12
Z
Density calculated (kg/dm3)
F000
1.181
2136
h range for data collection (ꢁ)
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness of fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
3.12–64.44
31059
9154
9154/0/667
0.810
R1 = 0.0323, wR2 = 0.0564
R1 = 0.0512, wR2 = 0.0611
0.136 and ꢀ0.150
3
˚
Largest diff. peak and hole (eA )
In the synthesis of the second diastereomer (R)-7, the
alkylation of the 3-position of galactose with (S)-14
was accompanied by the formation of lactone 24. In this
case, the lactone is particularly easily formed, because
the bulky adamantyl-methyl substituent adopts an equa-
torial position in the d-lactone ring (vs an axial position

A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
1051
Figure 4. X-ray crystal structure of 16: The asymmetric unit (c) contains stretched molecules (a) and conformationally collapsed conformers (b).
Nuclear magnetic resonance spectroscopy was per-
formed on a Bruker Avance 500 UltraShield spectrome-
ter at 500.13 MHz (1H) or 125.76 MHz (13C). Chemical
shifts are given in ppm and were calibrated on residual
solvent peaks37 or to tetramethyl silane as internal stan-
dard. Multiplicities were specified as s (singlet), d (dou-
blet), dd (doublet of a doublet), t (triplet), q (quartet),
dq (doublet of a quartet), quint. (quintublet) or m (mul-
tiplet). Interpretation of the spectra was performed
according to first order38 and higher order where
possible.
spectra were recorded on a Waters micromass ZQ
instrument. High resolution mass spectra were obtained
on an ESI Bruker Daltonics micrOTOF spectrometer
equipped with a TOF hexapole detector.
TLC was performed using silica gel 60 coated glass
plates containing fluorescence indicator (Merck KGaA,
Darmstadt, Germany) using either UV light (254 nm)
and by charring in aqueous KMnO4 solution or in a
molybdate solution (a 0.02 M solution of ammonium
cerium sulfate dihydrate and ammonium molybdate tet-
rahydrate in aqueous 10% H2SO4) with heating to
140 ꢁC for 5 min. Column chromatography was per-
formed using silica gel 60 (0.040–0.063 mm) from Fluka.
Microwave reactions were performed in a CEM Dis-
cover microwave apparatus. Hydrogenation reactions
were performed in a shaking apparatus (Parr Instru-
ments Company, Moline, Illinois, USA) in 250 mL or
500 mL bottles with 4 bar H2 pressure. Solvents were
purchased from Fluka and dried prior to use. DCM
was dried by filtration through basic aluminum oxide
(Fluka). Dioxane, DME, Et2O, and PhMe were dried
by distillation from sodium/benzophenone. DMF was
dried by distillation from calcium hydride and MeOH
by distillation from sodium methoxide.
The signals were assigned with the help of DEPT-135,
1H,1H-COSY/TOCSY and 1H,13C-HSQC/HMBC exper-
iments. Assignments are indicated according to IUPAC
nomenclature. For complex molecules, the following pre-
fixes for substructures are used: Ad (adamantyl), Cy
(cyclohexyl), Fuc (fucose), Gal (galactose), and Lac (lac-
tate). Ci indicates the ipso substituted carbons of aromatic
systems.
Optical rotations were measured on a Perkin Elmer 341
polarimeter in the indicated solvents in p.a. quality.
Microanalyses were performed at the Department of
Chemistry, University of Basel, Switzerland. ESI mass

1052
A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
OR
O
HO
RO
RO
O
O
O
O
(ii)
(i)
SEt
OBn
O
O
OBn
OBn
OBz
SEt
OBn
BnO
OBn
BnO
HO
HO
BzO
OBn
OBn
O
BnO
19
BzO
OBn
18
10[19]
9
20, R = Bz
21, R = H
(iii)
OH
OH
O
O
O
O
O
O
O
O
(iv)-(v)
(vi)-(viii)
O
O
O
ONa
OBn
HO
OH
HO
O
(R)-14
OBn
OH
OBn
BnO
OBn
OH
HO
(S)-22
(S)-7, rIC50 = 0.32
21
O
OH
O
O
O
O
HO
O
O
O
O
(vi)-(viii)
(iv)-(v)
O
O
O
ONa
HO
O
(S)-14
OH
OBn
OH
OBn
BnO
OH
OBn
HO
24
(R)-7, rIC50 > 10
Scheme 4. Reagents and conditions: synthesis of selectin antagonists containing adamantyl-lactic acid. (i) Br2, Bu4NBr, DCM, DMF, mol. sieves
˚
˚
4 A, ꢀ20 ꢁC–rt, 12 h (58%); (ii) DMTST, DCM, mol. sieves 4 A, rt, 5 days; (iii) NaOMe, MeOH, rt, overnight (85% for two steps); (iv) Bu2SnO,
+
MeOH, mol. sieves 3 A, reflux, 18 h; (v) CsF, DME, rt, 3 d (22: 21%; 24: 25%); (vi) H2, Pd(OH)2/C, dioxane–H2O, 4 bar, rt, 4 d; (vii) Na –ion
˚
exchange; (viii) NaOH, H2O; (ix) Sephadex-G15 ((S)-7: 92%; (R)-7: 31%).
rac-13 was separated using a Gilson preparative HPLC
apparatus equipped with a 5 · 50 cm Chiralpak AD col-
umn and a UV detector (210 nm). For elution, an iso-
cratic solvent system ethanol/hexanes 5/95 was used
(50 mL/min). Analytical chiral HPLC was performed
on a Chiralpak AD-H column (250 · 4.6 mm, 1 mL/
min, 210 nm). Enantiomeric excess was determined from
the peak areas after integration of the analytical
chromatograms.
to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK,
(fax: +44 (0)1223 336033 or e-mail: deposit@ccdc.
cam.ac.uk).
Biological data were obtained using the published ELI-
SA procedure with (S)-6 as reference compound.31
4.2. Ethyl 2-trimethylsilyloxy-acrylate (11)
To a solution of ethyl pyruvate (4.78 mL, 43.1 mmol)
and chlorotrimethylsilane (6.33 mL, 49.5 mmol) in
anhydrous diethylether (50 mL) was added triethyl-
amine (7.19 mL, 51.7 mmol) dropwise over a period of
10 min at 0 ꢁC. After stirring for 1 h at 0 ꢁC, the solution
was allowed to warm to rt and stirred for additional 3 h.
The reaction mixture was diluted with petrol ether
(250 mL), cooled to 0 ꢁC, and washed with cold brine
(3 · 50 mL). Drying over Na2SO4 and evaporation of
the solvent in vacuo gave the volatile crude product 11
as clear yellow oil (8.46 g), which was used in the next
The X-ray crystal structure of 16 was solved at Hoff-
mann-La Roche, Pharmaceutical Division, Pharma Re-
search 65/308, Basel, Switzerland. The diffraction
pattern was measured on a Gemini Ruby diffractometer
from Oxford Diffraction, Abingdon, UK, using Cu–Ka-
radiation with a wavelength of 1.54184 A. Structure
solution and refinement was performed using the ShelX
software39,40 (G. Sheldrick, Go¨ttingen, Germany).
˚
Crystallographic data (excluding structure factors) for
the structure in this paper have been deposited with
the Cambridge Crystallographic Data Centre as sup-
plementary Publication No. CCDC 626224. Copies of
the data can be obtained, free of charge, on application
1
step without further purification. H NMR (CDCl3): d
5.45, 4.82 (A, B of AB, J = 1.0 Hz, 2H, H3), 4.16 (q,
2
3J = 7.14 Hz, 2H, CH3CH2–), 1.25 (t, 3J = 7.15 Hz,
3H, CH3CH2–), 0.17 (s, 9H, (CH3)3Si–); 13C NMR

A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
1053
20
ee > 99.6%, ½aꢁ +3.1 (c 2.35, CHCl3); Benzyl (S)-3-(1-
20
(CDCl3): d 164.4 (C1), 147.2 (C2), 103.9 (C3), 61.2
(–CH2CH3), 14.1 (–CH2CH3), ꢀ0.1 ((CH3)3Si–).
D
adamantyl)-lactate ((S)-13). Analytical chiral HPLC:
tR = 12.01 min, optical purity: ee > 99.5%, ½aꢁD = ꢀ4.2
4.3. rac-3-(1-Adamantyl)-lactic acid (rac-12)
(c 1.67, CHCl3).
To
a
solution of 1-bromo-adamantane (7.90 g,
4.5. Benzyl (R)-3-(1-adamantyl)-2-(trifluoromethyl)sul-
fonyloxy-propionate ((R)-14)
36.7 mmol), 11 (13.8 g, 73.4 mmol), and AIBN (1.50 g,
9.18 mmol) in toluene (100 mL), tributyltinhydride
(11.7 mL, 44.0 mmol) was added. The reaction mixture
was refluxed for 25 h. After cooling to rt, a solution of
KF (5.11 g, 88.0 mmol) in water (150 mL) was added
and the heterogeneous mixture stirred vigorously over-
night. Ethyl acetate (1.5 L) was added, the phases were
separated, and the organic layer was washed with water
(300 mL) and brine (300 mL). After drying over
Na2SO4, the solvent was removed in vacuo to give the
crude ethyl ester. The residue was dissolved in a mixture
of aqueous 1 N NaOH (250 mL) and EtOH (100 mL).
After stirring overnight at 50 ꢁC, the ethanol was re-
moved in vacuo and the aqueous phase was diluted with
water (1 L), washed with DCM (2 · 350 mL), acidified
to pH 0 with aqueous 6 N HCl, and then extracted with
DCM (3 · 400 mL). Washing of the combined organic
layers with brine (200 mL), drying over Na2SO4, and
evaporation of the solvent gave rac-12 as a spectroscop-
ically pure, off-white solid (4.43 g, 54%) which was used
Ester (R)-13 (162 mg, 0.52 mmol) was dissolved in dry
DCM (3 mL) under argon and cooled to ꢀ20 ꢁC. 2,6-
Di-tert-butyl pyridine (197 lL, 0.88 mmol) was added,
followed by dropwise addition of triflic anhydride
(147 lL, 0.88 mmol). After 2 h at ꢀ20 ꢁC, the mixture
was diluted with DCM (30 mL) and washed with aque-
ous 1 M KH2PO4 solution (25 mL). The aqueous phase
was then extracted with DCM (3 · 40 mL) and the com-
bined organic layers were dried over Na2SO4. Evapora-
tion of the solvent in vacuo gave the crude product as a
colorless oil. Purification by column chromatography on
silica (PE/EE 20/1) gave pure (R)-14 as a colorless oil
(186 mg, 78%), which was used immediately for the next
1
reaction. Rf (PE/EE 20/1) 0.40; H NMR (CDCl3): d
7.38–7.35 (m, 5H, Ar–H), 5.27–5.21 (m, 3H, PhCH2,
2
H2), 1.96 (br s, 3H, H6), 1.83 (A of ABM, J = 15.4,
3J = 7.7 Hz, 1H, H3a), 1.74–1.53 (m, 13H, H3b, 12·
Ad-CH2); 13C NMR (CDCl3): d 168.1 (C1), 134.3 (Ar–
Ci), 128.8, 128.7, 128.6 (3Ar–C), 81.0 (C2), 68.2
(PhCH2), 45.8 (C3), 42.0 (3C, C5), 36.5 (3C, C7), 32.3
(C4), 28.3 (3C, C6).
1
without further purification. H NMR (CDCl3): d 4.40
(d, 3J = 9.4 Hz, 1H, H2), 1.98 (br s, 3H, H6), 1.77–
1.58 (m, 13H, Ad-CH2, H3b), 1.41 (A of ABM,
2
3J = 9.5, J = 14.5 Hz, 1H, H3a); 13C NMR (CDCl3): d
181.0 (C1), 67.5 (C2), 48.9 (C3), 42.6 (C5), 36.9 (C7),
32.5 (C4), 28.6 (C6); ESI-MS Calcd for C13H21O3
[M+H]+: 225.1; Found: 225.0.
4.6. (S)-Benzyl 3-(1-adamantyl)-2-(trifluoromethyl)sulfo-
nyloxy-propionate ((S)-14)
Two hundred and sixty milligrams (96%) of the title
compound was obtained using the same procedure as
4.4. rac-Benzyl 3-(1-adamantyl)-lactate (rac-13)
1
described for (R)-14. Rf and H/13C NMR see (R)-14.
To a suspension of rac-12 (679 mg, 3.03 mmol) in
MeOH/water (3:1) was added Cs2CO3 (591 mg,
1.82 mmol) under stirring to give a clear solution. The
solvents were removed in vacuo. After drying the residue
in high vacuum overnight, it was resuspended in anhy-
drous DMF (2.5 mL). Then benzyl bromide (2.15 mL,
18.2 mmol) was added and the suspension was stirred
for 20 h at rt. Removal of the solvent and purification
of the crude product by column chromatography on sil-
ica (PE/EE 100:0 > 85:15) gave pure rac-13 as a colorless
oil (690 mg, 73%). Rf (PE/EE 4/1) 0.67; 1H NMR
(CDCl3): d 7.40–7.35 (m, 5H, Ar–H), 5.22, 5.18 (A, B
of AB, 2J = 12.3 Hz, 2H, PhCH2), 4.36–4.33 (m, 1H,
H2), 1.96 (br s, 3H, H6), 1.71–1.56 (m, 13H, H3b, 12·
Ad-CH2), 1.37 (A of ABM, J = 9.3, J = 14.0 Hz, 1H,
H3a); 13C NMR (CDCl3): d 176.2 (C1), 135.3 (Ar–Ci),
128.6 (Ar–C), 128.5 (Ar–C), 128.2 (Ar–C), 67.8 (C2),
67.3 (PhCH2), 49.0 (C3), 42.7–42.6 (3C, C5), 37.0–36.9
(3C, C7), 32.4 (C4), 28.7–28.5 (3C, C6); ESI-MS calcd
for C20H26NaO3 [M+Na]+: 337.1; Found: 337.1; Anal.
calcd. for C20H26O3 + 1/4 H2O: C 75.32, H 8.38; Found:
C 75.32, H 8.26.
4.7. (S)-1-Phenylethyl (S)-3-(1-adamantyl)-lactamide (16)
and (S)-1-phenylethyl (R)-3-(1-adamantyl)-lactamide (17)
A microwave vial was charged with a magnetic stirring
bar, rac-12 (224 mg, 1.00 mmol), and (S)-a-methylben-
zylamine (15) (140 lL, 1.10 mmol). Dioxane (2 mL)
was added and the vial was sealed under argon. The
mixture was heated under microwave irradiation to
180 ꢁC for 70 min. After cooling to rt, the solvent was
evaporated, the residue was taken up in ethyl acetate
(100 mL) and washed with saturated aqueous K2CO3
(2 · 10 mL) and aqueous 0.5 N HCl (2 · 20 mL). The
organic layer was dried over Na2SO4. Evaporation of
the solvent gave the crude mixture of 16 and 17 as a light
yellow oil (279 mg, 85%). The diastereomers could be
separated by column chromatography on silica (PE/EE
3/1). ESI-MS Calcd for C21H29NNaO2 [M+Na]+:
350.2; Found: 350.2.
3
2
(S)-1-phenylethyl (S)-3-(1-adamantyl)-lactamide (16). Rf
20
(PE/EE 4/1) 0.55; ½aꢁ ꢀ59.7 (c 0.53, CHCl3); 1H
D
NMR (CDCl3): d 7.32–7.23 (m, 5H, Ar–H), 6.962 (d,
3J = 7.15 Hz, 1H, NH), 5.069 (m, 1H, MeCH–), 4.188
(M of ABM, J = 9.32 Hz, 1H, Lac-H2), 3.050 (br s,
With preparative HPLC on a 5 · 50 cm Chiralpak AD
column the two enantiomers (R)-13 and (S)-13 were sep-
arated: Benzyl (R)-3-(1-adamantyl)-lactate ((R)-13).
Analytical chiral HPLC: tR = 10.57 min, optical purity:
3
1H, OH), 1.95 (br s, 3H, Ad-H3), 1.700 (m, 4H, 3·
2
Ad-CH2, Lac-H3b), 1.623 (A0 of A0B0, J = 11.83 Hz,

1054
A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
3H, 3· Ad-CH2), 1.576 (s, 6H, Ad-CH2), 1.464 (d,
3J = 6.93 Hz, 3H, –CH3), 1.332 (A of ABM,
2J = 14.57, 3J = 9.45 Hz, 1H, Lac-H3a); 13C NMR
(CDCl3): d 174.15 (C1), 143.09 (Ar–Ci), 128.57 (2Ar–
C), 127.25 (pAr–C), 126.08 (2 Ar–C), 69.27 (C2), 49.34
(C3), 48.40 (PhCH–), 42.72 (3C, Ad-CH2), 36.88
(3C, Ad-CH2), 32.29 (Ad-C1), 28.57 (3C, Ad-C3),
21.83 (–CH3).
133.4, 133.1 (3C, Bz-Ci), 129.7–127.1 (Ar–C), 99.5 (Gal-
C1), 94.1 (Fuc-C1), 79.8 (CH), 79.1, 79.0, 76.4, 74.9
(CH), 74.8 (CH2), 73.6 (CH2), 73.0 (CH2), 72.5 (CH),
72.0 (CH), 70.0 (Gal-C2), 68.5 (Gal-C4), 67.7 (Gal-C6),
66.3 (Fuc-C5), 29.5 (Cy-CH2), 28.5 Cy-(CH2),
22.94 (Cy-CH2), 22.87 (Cy-CH2), 16.7 (Fuc-C6);
ESI-MS Calcd for C67H68NaO14 [M+Na]+: 1119.5;
Found: 1119.6.
(S)-1-phenylethyl (R)-3-(1-adamantyl)-lactamide (17). Rf
4.9. (1R,2R)-2-O-(2,3,4-tri-O-benzyl-a-L-fucopyranosyl)-
cyclohexyl 6-O-benzyl-b-D-galactopyranoside (21)
20
(PE/EE 4/1) 0.45; ½aꢁ ꢀ49.2 (c 0.035, CHCl3); 1H
D
NMR (CDCl3): d 7.35–7.24 (m, 5H, Ar–H), 6.881 (br
s, 1H, NH), 5.097 (m, 1H, MeCH–), 4.241 (M of
ABM, J = 9.50 Hz, 1H, Lac-H2), 1.96 (br s, 3H, Ad-
The protected pseudotrisaccharide 20 (9.70 g crude
material) was dissolved in dry MeOH (100 mL). When
3 M NaOMe in MeOH (3.5 mL) was added to the
solution, a white precipitate appeared which dissolved
after a few minutes. The solution was stirred at rt for
16 h and then neutralized with Dowex 50 · 8 ion ex-
change resin. The mixture was filtered and the solvent
evaporated to give the crude product as a colorless
oil. Purification by column chromatography on silica
(DCM/MeOH, gradient 25/1 to 10/1) yielded pure 21
as a white foam (5.53 g, 85% over two steps from
3
H3), 1.713–1.665 (m, 4H, 3· Ad-CH2, Lac-H3a), 1.624
2
(A0 of A0B0, J = 11.64 Hz, 3H, Ad-CH2), 1.574 (s, 6H,
3
Ad-CH2), 1.492 (d, J = 6.92 Hz, 3H, –CH3), 1.297 (B
2
3
of ABM, J = 14.56, J = 9.68 Hz, 1H, Lac-H3b); 13C
NMR (CDCl3): d 174.11 (C1), 142.97 (Ar–Ci), 128.62
(2Ar–C), 127.29 (pAr–C), 126.03 (2Ar–C), 69.40 (C2),
49.41 (C3), 48.38 (PhCH–), 42.73 (3C, Ad-CH2), 36.87
(3C, Ad-CH2), 32.32 (Ad-C1), 28.57 (3C, Ad-C3),
21.86 (–CH3).
1
10). Rf (DCM/MeOH 8/1) = 0.50; H NMR (CDCl3):
4.8. (1R,2R)-2-O-(2,3,4-tri-O-benzyl-a-L-fucopyranosyl)-
cyclohexyl 2,3,4-tri-O-benzoyl-6-O-benzyl-b-D-galacto-
pyranoside (20)
d 7.38–7.24 (m, 20 H, Ar–H), 4.97 (d, 3J = 3.6 Hz,
1H, Fuc-H1), 4.94 (A of AB, 2J = 11.6 Hz, 1H,
2
PhCH2), 4.81 (A0 of A0B0, J = 11.6 Hz, 1H, PhCH2),
2
4.75 (A00 of A00B00, J = 11.8 Hz, 1H, PhCH2), 4.68 (B0
2
Fucoside 10 (4.54 g, 8.52 mmol) and galactose donor 9
(5.88 g, 9.37 mmol) were dissolved in dry DCM
˚
(140 mL). Powdered activated molecular sieves (4 A,
of A0B0, J = 11.5 Hz, 1H, PhCH2), 4.67 (B00 of A00B00,
2J = 11.8 Hz, 1H, PhCH2), 4.59 (B of AB,
2J = 11.6 Hz, 1H, PhCH2), 4.52 (s, 2H, PhCH2), 4.33
(q, 3J = 6.3 Hz, 1H, Fuc-H5), 4.32 (d, 3J = 7.4 Hz,
1H, Gal-H1), 4.02 (dd, 3J = 3.6, 3J = 9.4 Hz, 1H,
Fuc-H2), 3.97 (s, 1H, Gal-H5), 3.96–3.95 (m, 1H,
Fuc-H3), 3.79–3.73 (m, 2H, 1· Cy-CH), 3.69 (dd,
1H, J = 5.3, J = 9.8 Hz), 3.63 (br s, 1H, Fuc-H4),
3.60–3.53 (m, 4H, 1· Cy-CH, Gal-H2), 2.72 (br s,
3H, OH), 2.07–1.98 (m, 2H, Cy-CH2), 1.70–1.65 (m,
2H, Cy-CH2), 1.42–1.18 (m, 4H, Cy-CH2), 1.09 (d,
3J = 6.4 Hz, 3H, Fuc-H6); 13C NMR (CDCl3): d
139.1, 138.8, 138.6, 137.8 (4C, 4 Bn-Ci), 128.5–127.3
(Ar–C), 100.3 (Gal-C1), 94.5 (Fuc-C1), 79.5 (CH),
78.0 (CH), 77.1 (CH), 76.34 (CH), 76.29 (CH), 74.8
(PhCH2), 73.6 (PhCH2), 73.4 (CH), 73.2 (CH), 73.1
(PhCH2), 73.0 (PhCH2), 71.1 (CH), 69.2 (Gal-C6),
68.6 (CH), 66.3 (CH), 30.3, 29.2, 23.3 (4C, 4 Cy-
CH2), 16.6 (Fuc-C6); Anal. calcd. for C46H56O11 + 2/
3 H2O: C 69.33, H 7.25; Found: C 69.39, H 7.22;
ESI-MS Calcd for C46H56NaO11 [M+Na]+: 807.4;
Found: 807.4.
15.0 g) were added and the mixture was stirred for 3.5 h
under argon at rt. DMTST (25.6 mmol, 6.60 g) was dis-
solved in dry DCM (40 mL) and powdered activated
˚
molecular sieves (4 A, 3.75 g) were added and this suspen-
sion was stirred for 2 h under argon at rt as well. Then the
two suspensions were combined and stirred for 5 days at rt
under argon. The mixture was filtered over Celite. After
washing of the organic layer with 8% aqueous NaHCO3
(30 mL), the aqueous layer was extracted with DCM (2·
40 mL). The combined organic layers were dried over
Na2SO4 and the solvent was removed in vacuo. The crude
product 20 was obtained as white foam (9.95 g). It was
used without further purification. A small sample was
purified by column chromatography on silica (PE/EE 5/
1) for analyses. Rf (PE/EE 4/1) 0.11; 1H NMR (CDCl3):
d 7.91 (m, 2H, Bz-H2/5), 7.86 (m, 2H, Bz0-H2/5), 7.71
(m, 2H, Bz00-H2/5), 7.48–7.02 (m, 29 H, Ar–H), 5.86 (br
s, 1H, Gal-H4), 5.60 (dd, 3J = 8.1, 3J = 10.2 Hz, 1H,
3
3
Gal-H2), 5.43 (dd, J = 3.2, J = 10.4 Hz, 1H, Gal-H3),
4.89 (A of AB, J = 11.5 Hz, 1H, PhCH2), 4.86 (br s,
2
3
1H, Fuc-H1), 4.77 (d, J = 7.9 Hz, 1H, Gal-H1), 4.73
4.10. Benzyl (2S)-3-(1-adamantyl)-2-O-{1-O-[(1R,2R)-2-
O-(2,3,4-tri-O-benzyl-a-L-fucopyranosyl)-cyclohexyl] 6-
O-benzyl-b-D-galactopyranos-3-yl}-propionate (22)
(A0 of A0B0, 2J = 11.7 Hz, 1H, PhCH2), 4.68 (A00 of A00B00,
2J = 11.0 Hz, 1H, PhCH2), 4.59 (B00 of A00B00,
2J = 12.0 Hz, 1H, PhCH2), 4.54 (B of AB, B0 of A0B0,
2J = 11.6 Hz, 2H, PhCH2), 4.89 (q, 3J = 6.1 Hz, 1H,
Fuc-H5), 4.38, 4.25 (A000,B000 of A000B000, 2J = 11.9, 2H,
PhCH2), 3.99–3.94 (m, 2H, Fuc-H2, Gal-H5), 3.70 (m,
1H, Cy-CH), 3.64 (s, 1H, Fuc-H4), 3.59–3.48 (m, 4H,
Fuc-H3, Gal-H6, Cy-CH), 1.86 (br s, 2H, Cy-CH2),
Compound 21 (199 mg, 253 lmol) and dibutyltinoxide
(69.3 mg, 278 lmol) were dissolved in dry MeOH
˚
(15 mL). Activated molecular sieves 3 A (400 mg) were
added to the solution, which was then refluxed under ar-
gon for 17 h. Filtration of the suspension over Celite,
evaporation of the solvent, and drying for 27 h in high
vacuum gave a yellow oily substance (258 mg). This res-
idue was suspended in dry DME (6 mL) under argon.
3
1.55–1.02 (m, 6H, Cy-CH2), 1.22 (d, J = 6.8 Hz, 3H,
Fuc-H6); 13C NMR (CDCl3): d 165.5, 165.4, 165.0 (3C,
Ph-CO2–), 139.03, 139.01, 138.7, 137.4 (4C, Bn-Ci),

A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
1055
2
Extensively dried CsF (50 mg, 0.33 mmol) was added
and the reaction mixture was stirred for 25 min at rt.
Then, a solution of dry (R)-14 (134 mg, 300 lmol) in
dry DME (6 mL) was added to the reaction, which
turned turbid upon addition, but cleared again after
2.5 h. After stirring for 4 d at rt, the reaction mixture
was concentrated and the residue was purified by two
consecutive column chromatographies on silica (1:
PE/EE 10/1 to 2/1, 2: DCM/MeOH 50/1) to yield 22
as a white solid (58 mg, 21%) and, as a byproduct,
of A0B0, J = 12.9 Hz, 1H, PhCH2), 4.67 (B00 of A00B00,
2J = 12.1 Hz, 1H, PhCH2), 4.61 (B of AB, J = 11.6 Hz,
1H, PhCH2), 4.56–4.50 (m, 2H, Gal-H1, Lac-H2), 4.49
2
3
(s, 2H, PhCH2), 4.44 (q, J = 7.1 Hz, 1H, Fuc-H5), 4.37
3
(t, J = 9.7 Hz, 1H, Gal-H2), 4.15 (s, 1H, Gal-H4), 4.03
(dd, 3J = 3.5, 3J = 10.1 Hz, 1H, Fuc-H2), 3.97 (dd,
3
3J = 2.7, J = 10.1 Hz, 1H, Fuc-H3), 3.78–3.75 (m, 2H,
Cy-CH, Gal-H6a), 3.68–3.59 (m, 4H, Cy-CH, Fuc-H4,
Gal-H5/6b), 3.49 (dd, 3J = 2.9, 3J = 9.7 Hz, 1H, Gal-
H3), 2.36 (br s, 1H, OH), 2.00–1.98 (m, 5H, 2· Cy-CH2,
2
3
(S)-benzyl 3-(1-adamantyl)-2-fluoro-propionate (23,
3· Ad-H3), 1.84 (dd, J = 14.8, J = 2.0 Hz, 1H, Lac-
H3a), 1.73–1.51 (m, 15H, 2H of Cy-CH2, 12H of Ad-
CH2, Lac-H3b), 1.49–1.17 (m, 4H, 4H of Cy-CH2), 1.11
(d, 3J = 6.5 Hz, 3H, Fuc-H6); 13C NMR (CDCl3): d
169.6 (Lac-C1), 139.2, 138.9, 138.7, 137.5 (4C, Bn-Ci),
128.5–127.2 (Ar–C), 98.1 (Gal-C1), 94.5 (Fuc-C1), 79.7
(Fuc-C3), 78.5 (Cy-CH), 78.2 (Cy-CH), 76.7 (Fuc-C2),
76.4 (Gal-H2), 76.0 (Fuc-H4), 75.7 (Lac-C2), 74.82
(Gal-H3), 74.79 (PhCH2), 73.7 (CH), 73.0 (2C, PhCH2),
72.9 (PhCH2), 68.4 (Gal-C6), 66.9 (Gal-C4), 66.0 (Fuc-
C5), 46.9 (Lac-C3), 42.6 (3C, Ad-C3), 36.8 (3C, Ad-C2),
32.4 (Ad-C1), 29.5 (Cy-CH2), 28.7 (Cy-CH2), 28.5 (3·
Ad-C4), 23.0 (2C, Cy-CH2), 16.6 (Fuc-C6); ESI-MS
Calcd for C59H72NaO12 [M+Na]+: 995.5; Found:
995.7.
20
D
48 mg, 51%). 22: Rf (PE/EE 2/1) 0.50; ½aꢁ ꢀ48.3 (c
1
1.05, CHCl3); H NMR (CDCl3): d 7.37–7.20 (m, 25
H, Ar–H), 5.18, 5.11 (A, B of AB, J = 12.2 Hz, 2H,
2
2
PhCH2), 4.94 (A0 of A0B0, J = 11.6 Hz, 1H, PhCH2),
3
4.91 (d, J = 2.5 Hz, 1H, Fuc-H1), 4.80 (A00 of A00B00,
2J = 11.6 Hz, 1H, PhCH2), 4.75 (A000 of A000B000,
2J = 12.0 Hz, 1H, PhCH2), 4.68 (m, 2H, PhCH2),
4.60 (B0 of A0B0, 2J = 11.6 Hz, 1H, PhCH2), 4.54–
4.46 (m, 3H, 2H of PhCH2, Lac-H2), 4.43–4.40 (m,
1H, Fuc-H5), 4.28 (d, 3J = 7.7 Hz, 1H, Gal-H1),
3
4.04–3.94 (m, 2H, Fuc-H2), 3.85 (d, J = 2.8 Hz, 1H,
Gal-H4), 3.79–3.63 (m, 6H, 1H of Cy-CH, Fuc-H3/4,
Gal-H2/6a,b), 3.59–3.53 (m, 1H, Cy-CH), 3.48 (t,
3J = 6.0 Hz, 1H, Gal-H5), 3.27 (dd, 3J = 3.2,
3J = 9.2 Hz, 1H, Gal-H3), 2.89 (br s, 1H, OH), 2.48
(br s, 1H, OH), 1.97 (br s, 2H, Cy-CH2), 1.91 (br s,
3H, Ad-H3), 1.72–1.40 (m, 16H, 1H of Cy-CH2, 12H
of Ad-CH2, Lac-H3a,b), 1.38–1.09 (m, 4H, 4H of
Cy-CH2), 1.06 (d, 3J = 6.5 Hz, 3H, Fuc-H6); 13C
NMR (CDCl3): d 174.9 (Lac-C1), 139.2, 138.9, 138.8,
138.2, 135.3 (5C, Bn-Ci), 128.7–126.6 (Ar–C), 100.0
(Gal-C1), 94.9 (Fuc-C1), 81.2 (Gal-C3), 79.7 (CH),
78.1 (CH), 77.2 (CH), 76.32 (CH), 76.28 (CH), 76.1
(PhCH2), 74.9 (CH), 73.6 (PhCH2), 73.3 (Gal-C5),
73.0 (PhCH2), 71.4 (CH), 69.1 (CH2), 67.1 (Gal-C4),
66.9 (Ph-CH2–O–CO–), 66.1 (Fuc-C5), 47.8 (Lac-C3),
42.5 (3· Ad-C3), 36.8 (3· Ad-C2), 32.5 (Ad-C1),
29.9 (Cy-CH2), 29.3 (Cy-CH2), 28.5 (3· Ad-C4), 23.3
(2· Cy-CH2), 16.6 (Fuc-C6); ESI-MS Calcd for
C66H80NaO13 [M+Na]+: 1103.6; Found: 1103.8.
4.12. Sodium (2S) 3-(1-adamantyl)-2-O-{1-O-[(1R,2R) 2-
O -(a-L-fucopyranosyl) cyclohexyl] b-D-galactopyranos-3-
yl}-propionate ((S)-7)
Compound 22 (26.3 mg, 24 lmol) and Pd(OH)2/C
(20 mg) were suspended in dioxane/water (4/1, 3 mL).
This suspension was hydrogenated at rt for 3 d. The sol-
vents were removed in vacuo and the residue taken up
in MeOH. Filtration over Celite and evaporation of the
solvent gave the crude product (22 mg). Purification by
column chromatography on silica (DCM/MeOH/H2O
10/4/0.8), Dowex 50 · 8 ion exchange chromatography
(Na+ form), Sephadex G-15 size exclusion chromatogra-
phy, and microfiltration afforded (S)-7 (14.8 mg, 92%)
t
as white solid after a final lyophilization from BuOH/
20
D
H2O. Rf (DCM/MeOH/H2O 10/4.8/0.5) 0.34; ½aꢁ ꢀ64.5
20
D
1
Benzyl (S)-3-(1-adamantyl)-2-fluoro-propionate (23). ½aꢁ
(c 0.74, MeOH); H NMR (MeOH-d4): d 4.86 (m, 1H,
Fuc-H1), 4.58 (q, 1H, 3J = 6.2 Hz, Fuc-H5), 4.32 (d,
1H, 3J = 7.8 Hz, Gal-H1), 3.96 (d, 1H, 3J = 8.9 Hz, Lac-
ꢀ6.4 (c 2.3, CHCl3); 1H NMR (CDCl3): d 7.39–7.33 (m,
2
5H, Ar–H), 5.23, 5.19 (A, B of AB, J = 12.2 Hz, 2H,
PhCH2), 5.09 (ddd, 2J(H–F) = 50.2, 3J = 2.3,
3J = 9.6 Hz, 1H, H2), 1.97 (br s, 3H, H6), 1.75–1.53 (m,
14H, H3a,b, 12H of Ad-CH2); ESI-MS Calcd for
C20H25FNaO2 [M+Na]+: 339.2; Found: 339.2.
H2), 3.89 (dd, 1H, J = 3.3, J = 10.1 Hz, Fuc-H3), 3.84
(d, 1H, J = 2.3 Hz, Gal-H4), 3.76 (m, 1H, Gal-H6a),
3
3
3
3.73–3.65 (m, 4H, 1· Cy-CH, Fuc-H2/4, Gal-H6b),
3.58–3.52 (m, 2H, Gal-H2, 1· Cy-H), 3.47 (t, 1H,
3J = 6.1 Hz, Gal-H5), 3.23 (dd, 1H, 3J = 3.0,
3J = 9.4 Hz, Gal-H3), 2.09–2.03 (m, 2H, Cy-CH2), 1.93
(br s, 3H, Ad-H3), 1.74–1.61 (m, 14H, 2· Cy-CH2, 12·
Ad-CH2), 1.60–1.41 (m, 2H, Lac-H3a,b), 1.39–1.25 (m,
4.11. Lactone derivative of benzyl (2R) 3-(1-adamantyl)-
2-O-{1-O-[(1R,2R) 2-O-(2,3,4-tri-O-benzyl-a-L-fucopyr-
anosyl) cyclohexyl] 6-O-benzyl-b-D-galactopyranos-3-yl}-
propionate (24)
4H, 4· Cy-CH2), 1.18 (d, 3H, 3J = 6.5 Hz, Fuc-H6); 13
C
NMR (MeOH-d4): d 184.00 (Lac-C1), 102.6 (Gal-C1),
97.0 (Fuc-C1), 84.5 (Gal-C3), 80.2 (Lac-C2), 79.2 (CH),
77.2 (CH), 75.9 (Gal-C5), 73.8 (CH), 71.7 (CH), 71.5
(Fuc-C3), 69.9 (CH), 67.7 (Gal-C4), 67.4 (Fuc-C5), 63.2
(Gal-C6), 50.1 (Lac-C3), 43.9 (3· Ad-C3), 38.2 (3· Ad-
C2), 33.5 (Ad-C1), 30.9 (Cy-CH2), 30.3 (3· Ad-C4),
30.0 (Cy-CH2), 24.5 (2· Cy-CH2), 16.6 (Fuc-C6); HR-
MS Calcd for C31H49O13 [MꢀH]ꢀ: 629.3173; Found:
629.3195.
Compound 24 was prepared in analogy to 22 starting
from 21 (51 mg, 65 lmol). Purification by column chro-
matography (PE/EE 9/1 > 0/10) yielded the pure lactone
20
1
24 (62 mg, 25%): ½aꢁ ꢀ62.4 (c 0.25, CHCl3); H NMR
D
(CDCl3): d 7.39–7.26 (m, 20 H, Ar–H), 4.95 (A of AB,
2J = 13.0 Hz, 1H, PhCH2), 4.93 (d, 3J = 3.6 Hz, 1H,
2
Fuc-H1), 4.84 (A0 of A0B0, J = 11.7 Hz, 1H, PhCH2),
4.76 (d, A00 of A00B00, 2J = 11.9 Hz, 1H, PhCH2), 4.70 (B0

1056
A. Titz et al. / Bioorg. Med. Chem. 16 (2008) 1046–1056
9. Lin, Y.-C.; Hummel, C. W.; Huang, D.-H.; Ichikawa, Y.;
Nicolau, K. C.; Wong, C.-H. J. Am. Chem. Soc. 1992, 114,
5452.
10. Rinnbauer, M.; Ernst, B.; Wagner, B.; Magnani, J.; Benie,
A. J.; Peters, T. Glycobiology 2003, 13, 435.
11. Scheffler, L.; Ernst, B.; Katopodis, A.; Magnani, J. L.;
Wang, W. T.; Weisemann, R.; Peters, T. Angew. Chem.,
Int. Ed. 1995, 34, 1841.
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459.
13. Brandley, B. K.; Kiso, M.; Abbas, S.; Nikrad, P.;
Srivasatava, O.; Foxall, C.; Oda, Y.; Hasegawa, A.
Glycobiology 1993, 3, 633.
14. Ramphal, J. Y.; Zheng, Z.-L.; Perez, C.; Walker, L. E.;
DeFrees, S. A.; Gaeta, F. C. A. J. Med. Chem. 1994, 37,
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15. Stahl, W.; Sprengard, U.; Kretzschmar, G.; Kunz, H.
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16. (a) Kolb, H. C.; Ernst, B. Chem. Eur. J. 1997, 3, 1571; (b)
Kolb, H. C.; Ernst, B. Pure Appl. Chem. 1997, 69, 1879.
17. Thoma, G.; Magnani, J. L.; Patton, J. T.; Ernst, B.;
Jahnke, W. Angew. Chem., Int. Ed. 2001, 40, 1941.
18. Somers, W. S.; Tang, J.; Shaw, G. D.; Camphausen, R. T.
Cell 2000, 103, 467.
19. Prodger, J. C.; Bamford, M. J.; Bird, M. I.; Gore, P. M.;
Holmes, D. S.; Priest, R.; Saez, V. Bioorg. Med. Chem.
1996, 4, 793.
4.13. Sodium (2R)-3-(1-adamantyl)-2-O-{1-O-[(1R,2R)-
2-O -(a-L-fucopyranosyl) cyclohexyl] b-D-galactopyranos-
3-yl}-propionate ((R)-7)
Hydrogenation was performed in analogy to (S)-7. The
obtained lactone was opened by stirring in aqueous
NaOH overnight at rt. After column chromatography
on silica (DCM/MeOH/H2O 10/4/0.8), (R)-7 (8.2 mg,
31%) was obtained as a white solid, which was taken
up in MeOH (2 mL), microfiltered, dried, and lyophi-
t
lized from BuOH/H2O: Rf (DCM/MeOH/H2O 10/4.8/
20
0.5) 0.58; ½aꢁ ꢀ31.9 (c 0.42, MeOH); 1H NMR
D
(MeOH-d4):
d 4.89 (m, 1H, Fuc-H1), 4.53 (q,
3J = 6.4 Hz, 1H, Fuc-H5), 4.33 (d, 3J = 7.6 Hz, 1H,
Gal-H1), 4.25 (d, 3J = 5.9 Hz, 1H, Lac-H2), 4.09 (d,
3J = 3.0 Hz, 1H, Gal-H4), 3.87 (dd, 3J = 3.3,
3J = 10.1 Hz, 1H, Fuc-H3), 3.80–3.62 (m, 6H, Cy-CH,
3
3
Fuc-H2/4, Gal-H2/6a,b), 3.58 (dt, J = 3.9, J = 8.8 Hz,
1H, Cy-CH), 3.42 (t, 3J = 5.7 Hz, 1H, Gal-H5), 3.37
(dd, 3J = 3.1, 3J = 9.8 Hz, 1H, Gal-H3), 2.04 (d,
J = 12.8 Hz, 2H, Cy-CH2), 1.95 (br s, 3H, Ad-H3),
1.75–1.64 (m, 14H, 2H of Cy-CH2, 12H of Ad-CH2),
1.57 (d, J = 5.8 Hz, 2H, Lac-H3a,b), 1.45–1.25 (m, 4H,
3
4H of Cy-CH2), 1.18 (d, J = 6.6 Hz, 3H, Fuc-H6); 13C
NMR (MeOH-d4): d 183.7 (Lac-C1), 102.9 (Gal-C1),
97.0 (Fuc-C1), 81.6 (Gal-C3), 79.2 (CH), 77.7 (Lac-
C2), 77.0 (Cy-CH), 76.0 (Gal-C5), 73.8 (Fuc-C4), 71.6
(Fuc-C3), 71.5 (Fuc-C2), 70.0 (CH), 67.9 (Gal-C4),
67.4 (Fuc-C5), 62.9 (Gal-C6), 49.5 (Lac-C3), 43.9 (3·
Ad-C3), 38.1 (3· Ad-C2), 33.5 (Ad-C1), 30.8 (Cy-
CH2), 30.3 (3C, Ad-C4), 29.7, 24.3, 24.2 (3C, Cy-
CH2), 16.6 (Fuc-C6); ESI-MS Calcd for C31H50NaO13
[M+H]+: 653.3; Found: 653.3.
20. Ernst, B. unpublished data.
21. Kolb, H.C., WO 9701569, 1997.
22. Porro, M. Dissertation, University of Basel, 2006.
23. Vedani, A.; Huhta, D. W. J. Am. Chem. Soc. 1990, 112,
4759.
24. Ernst, B.; Wagner, B.; Baisch, G.; Katopodis, A.; Winkler,
T.; Ohrlein, R. Can. J. Chem. 2000, 78, 892.
25. Ohno, M.; Ishizaki, K.; Eguchi, S. J. Org. Chem. 1988, 53,
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26. Iannelli, M.; Alupei, V.; Ritter, H. Tetrahedron 2005, 61,
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27. Lemieux, R. U.; Hendriks, K. B.; Stick, R. V.; James, K.
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28. Fugedi, P.; Garegg, P. J. Carbohydr Res. 1986, 149, C9.
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29. Grindley, T. B. Adv. Carbohyd. Chem. Biochem. 1998, 53,
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30. Kretzschmar, G.; Toepfer, A.; Huels, C.; Krause, M.
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We are grateful to the Swiss National Science Founda-
tion and Glycomimetics Inc. for financial support. The
authors thank Bea Wagner for technical support and
Dr. Petur Dalsgaard for the acquisition of the HR-MS
spectra. We also thank W. Kirsch for high accuracy ele-
mental analysis measurements.
32. Goodman, J. M.; Still, W. C. J. Comput. Chem. 1991, 12,
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References and notes
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