Small molecules as structural and functional mimics of sialyl Lewis X tetrasaccharide in selectin inhibition: A remarkable enhancement of inhibition by additional negative charge and/or hydrophobic group

Article abstract of DOI:10.1021/ja970920q

Several sialyl Lewis X (SLe(X))) mimics that contain the essential functional groups for receptor interaction and a negative charge or a hydrophobic group have been developed as inhibitors of E-, P-, and L-selectins. Some of the mimics exhibit selectin in

Full text of DOI:10.1021/ja970920q

8152
J. Am. Chem. Soc. 1997, 119, 8152-8158
Small Molecules as Structural and Functional Mimics of Sialyl
Lewis X Tetrasaccharide in Selectin Inhibition: A Remarkable
Enhancement of Inhibition by Additional Negative Charge
and/or Hydrophobic Group
Chi-Huey Wong,*,† Francisco Moris-Varas,† Shang-Cheng Hung,†
Thomas G. Marron,† Chun-Cheng Lin,† Ke Wei Gong,‡ and
Gabriele Weitz-Schmidt‡
Contribution from the Department of Chemistry and the Skaggs Institute for Chemical Biology,
The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, and
NoVartis Pharma AG, CH-4002 Basel, Switzerland
ReceiVed March 24, 1997X
Abstract: Several sialyl Lewis X (SLex) mimics that contain the essential functional groups for receptor interaction
and a negative charge or a hydrophobic group have been developed as inhibitors of E-, P-, and L-selectins. Some
of the mimics exhibit selectin inhibition activities 103-104-fold more potent than does the natural ligand tetrasaccharide,
with IC50 in the low micromolar to high nanomolar range. The syntheses of these mimics are relatively simple,
using TMSOTf-Ac2O mediated C-glycosylation with concurrent selective deprotection of the primary benzyl group
and enzymatic aldol addition reactions as key steps.
Current interest in the study of selectin-sialyl Lewis X
tetrasaccharide (SLex) interaction,1 a recognition process in-
volved in the adhesion leukocytes to vascular endothelial cells
during inflammatory responses, has led to an intensive search
for small molecules as inhibitors of selectin binding and as
potential drug candidates for the treatment of reperfusion injury
and other inflammatory disorders.2 Development of carbohydrate-
based therapy is, however, hindered by the complication that
most proteins bind carbohydrates with weak affinity3 and that
synthesis of complex carbohydrates is a rather expensive and
difficult process. Understanding the molecular basis of protein-
carbohydrate interaction is therefore of fundamental importance
† The Scripps Research Institute.
‡ Novartis Pharma AG.
X Abstract published in AdVance ACS Abstracts, August 15, 1997.
(1) For recent review see: (a) Sears, P.; Wong, C.-H. Proc. Natl. Acad.
Sci. U.S.A. 1996, 93, 12086-12093. (b) Kiessling, L. L.; Pohl, N. L. Chem.
Biol. 1996, 3, 71-77. (c) Lasky, L. A. Annu. ReV. Biochem. 1995, 64, 113-
139. (d) Bertozzi, C. R. Chem. Biol. 1995, 2, 703-708. (e) Rosen, S. D.;
Bertozzi, C. R. Curr. Opin. Cell. Biol. 1994, 6, 663-673. (f) Bevilacqua,
M. P. Annu. ReV. Immunol. 1993, 11, 767-804.
Figure 1. Model showing the structure and functional groups of SLex
interacting with E-selectin (0), and the groups recognized by P- (b)
and L-selectin (2). Both E- and P-selectins bind SLex in a similar
manner (as indicated). L-selectin recognized approximately the free
form of SLex, with the NeuAc-CO2H pointing above the plane.
(2) For representative examples, see: (a) Dasgupta, F.; Rao, B. N. N.
Exp. Opin. InVest. Drugs 1994, 3, 709-724. (b) Kogan, T. P.; Dupre, B.;
Keller, K. M.; Scott, I. L.; Bui, H.; Market, R. V.; Beck, P. J.; Voytus, J.
A.; Bevelle, B. M.; Scott, D. J. J. Med. Chem. 1995, 38, 4976-4984. (c)
Toepfer, A.; Kretzschmar, G.; Bartnik, E. Tetrahedron Lett. 1995, 36, 9161-
9164. (d) Kogan, T. P.; Dupre, B.; Keller, K. M.; Scott, I. L.; Bui, H.;
Market, R. V.; Beck, P. J.; Voytus, J. A.; Revelle, B. M.; Scott, D. J. Med.
Chem. 1996, 38, 4976-4984. (e) Hiramatsu, Y.; Tsujishita, H.; Kondo, H.
J. Med. Chem. 1996, 39, 4547-4553. (f) Marron, T. G.; Woltering, T. J.;
Weitz-Schmidt, G.; Wong, C.-H. Tetrahedron Lett. 1996, 37, 9037-9040.
(g) Woltering, T. J.; Weitz-Schmidt, G.; Wong, C.-H. Tetrahedron Lett.
1996, 37, 9033-9036. (h) Wu, S.-H.; Shimazaki, M.; Lin, C.-C.; Moree,
W. J.; Weitz-Schmidt, G.; Wong, C.-H. Angew. Chem., Int. Ed. Engl. 1996,
35, 88-90. (i) Lin, C.-C.; Shimazaki, M.; Heck, M.-P.; Aoki, S.; Wang,
R.; Kimura, T.; Ritzen, H.; Takayama, S.; Wu, S.-H.; Weitz-Schmidt, G.;
Wong, C.-H. J. Am. Chem. Soc. 1996, 118, 6826-6840. (j) Hiruma, K.;
Kajimoto, T.; Weitz-Schmidt, G.; Ollmann, I.; Wong, C.-H. J. Am. Chem.
Soc. 1996, 118, 9265-9270. (k) Tsujishita, H.; Hiramatsu, Y.; Kondon,
N.; Ohmoto, H.; Kondo, H.; Kiso, M.; Hasegawa, A. J. Med. Chem. 1997,
40, 362. (l) Ohmoto, H.; Nakamura, K.; Inoue, T.; Kondo, N.; Inoue, Y.;
Yoshino, K.; Kondo, H. J. Med. Chem. 1996, 39, 1339.
for development of small molecule inhibitors that are structural
and functional mimics of natural ligands and are more effective
and accessible than the parent structures.
Figure 1 indicates the structure and essential functional
groups4 of SLex recognized by E-selectin5 and also the groups
recognized by P- and L-selectins.1e,4 A recent NMR study5c
suggests that the free and bound states of the Lex moiety of
SLex are basically the same in the three selectin-ligand
complexes while the NeuAc-carboxylate orientation in the
L-selectin complex differs from that of the E- and P-selectin
complex. These recognition models have helped the develop-
(4) (a) Bradley, B. K.; Kiso, M.; Abbas, S.; Nikrad, P.; Strivastava, O.;
Foxall, C.; Oda, Y.; Hasegawa, A. Glycobiology 1993, 3, 633-639. (b)
Stahl, W.; Spremgard, U.; Kretzschmar, G.; Kunz, H. Angew. Chem., Int.
Ed. Engl. 1994, 33, 2096-2098. (c) De Frees, S. A.; Gaeta, F. C. A.; Lin,
Y. C.; Ichikawa, Y.; Wong, C.-H. J. Am. Chem. Soc. 1993, 115, 7549-
7550.
(3) Lemieux, R. U. Acc. Chem. Res. 1996, 29, 373-380. Lee, Y. C.;
Lee, R. T. Acc. Chem. Res. 1995, 28, 321-327. Toone, E. J. Curr. Opin.
Struct. Biol. 1994, 4, 719-728.
S0002-7863(97)00920-7 CCC: $14.00 © 1997 American Chemical Society

Mimics of Sialyl Lewis X in Selectin Inhibition
J. Am. Chem. Soc., Vol. 119, No. 35, 1997 8153
Scheme 1a
a Reagents and conditions: (a) allyl-TMS (2 equiv)/MeCN/TMSOTf
(0.5 equiv) 0 °C f 25 °C, then Ac2O, (b) NaOMe (0.3 equiv)/MeOH,
25 °C; NaH (1.2 equiv)/THF RBr (1.2 equiv), 0 °C, 24 h, (c) PdCl2,
benzene, 80 °C, 24 h.
with the hydrophobic portion of E- and P-selectins2k and
therefore to enhance binding. As a result, a dramatic increase
in inhibition against all three selectins was observed. Removing
the carboxylate from 3 and placing a more constrained benzoic
acid in the NeuAc-CO2H position still shows an impressive
activity, indicating the significant effect of the hydrophobic
group. Compounds 4 and 4a were also prepared for evaluation
in consideration of our previous result from the related structure
5 which binds more tightly than does SLex to E-selectin.2f
Surprisingly, the phosphate-containing O-linked mannoside is
104-fold more potent than SLex against P-selectin (IC50 ) 0.6
µM). This remarkable enhancement of inhibition may be due
to some additional interactions of the aglycon groups with some
other groups of P-selectin. One possibility is the ionic interac-
tion of the phosphate with Lys111 and Lys113 which are close
to the NeuAc-CO2H and the Gal-2-OH groups.2k Another
possibility is that a nucleophile in the active site may interact
with the carbonyl group, as some Lex-3′-phosphate derivatives
did not significantly improve the affinity.2l The C-linked
phosphate 4a, structurally related to 5, was found less active
than 4, though much more potent than SLex against P- and
L-selectins. For comparison, the inhibition activities of 6 and
6a prepared previously2g were also included.
Figure 2. Designated SLex mimetics.
Table 1. IC50 (µM) Values in Selectin Inhibitiona
1
2
3
3a
74 100 800 160
0.6
5 ndc
4
4a
5
6
6a
300 37
2500
40 ndc >3000 190 1300 (3900)b
SLex
E- 110 100 40
500 (720)b
P- ndc ndc 2.2
5
7 >3000 (8000)b
L- ndc ndc 7.6 100 95
a Determined in a cell-free assay (ref 7) based on the polymeric SLea
interaction with a microtiter plate coated selectin. The values represent
the average of three measurements, with (10% error. b The number is
taken from the NMR study (ref 5c). c Not determined.
ment of small molecules that mimic SLex, in interaction with
its receptors,2 and further enhancement of inhibition has been
achieved with addition of a hydrophobic group2b,k to the mimic
or with the use of multivalent strategy.1b,6
The synthesis of these mimics are relatively simple as
indicated in Schemes 1-4. Of particular interest is the synthesis
of key intermediate 8 from 7 via a one-pot TMSOTf-Ac2O
mediated C-allylation with a concurrent debenzylation/acety-
lation of the 6-benzyl group, which provides an easy access to
C-glycosides with alkyl substituents at the C-6 position. This
reaction was found to be also applicable to other benzylated
hexoses.9 Another interesting reaction is the one-step enzymatic
aldol reaction to give 4 (Scheme 4) and 4a using the O- and
C-linked aldehyde substrates, respectively. The other diaster-
eomers of 4 with different aglycon configurations were also
prepared using different aldolases,10 but all the products exhibit
weaker inhibition than 4 against P-selectin.
In this study, we have developed a new series of mannose-
based SLex mimics (1-4), as shown in Figure 2, some of which
(e.g., 3 and 4) exhibit the most potent inhibition activity7 (in
the low micromolar range) known to date (Table 1). Compound
1, a peptide disaccharide, contains the six essential functional
groups required for SLex recognition, and as expected, its
activity is comparable to the natural ligand. Compounds 2 and
3 employ a carboxylate group to replace the Gal residue, with
the hope that it may also interact with the nearby Lys111 and
Lys113 residues in E- and P-selectins.2e,3b Mimetic 3 also
contains a long-chain hydrophobic group8 designed to interact
(5) For the SLex structure bound to E-selectin, see: (a) Scheffler, K.;
Ernst, B.; Katopodis, A.; Magnani, J. L.; Wang, W. T.; Weisemann, R.;
Peters, T. Angew. Chem., Int. Ed. Engl. 1995, 34, 1841-1844. (b) Cooke,
R. M.; Hale, R. S.; Lister, S. G.; Shah, G.; Weir, M. P. Biochemistry 1994,
33, 10591-10596. For SLex bound to E-, P-, and L-selectin, see: (c) Poppe,
L.; Brown, G. S.; Philo, J. S.; Nikrad, P. V.; Shah, B. H. J. Am. Chem.
Soc. 1997, 119, 1727. The dissociation constants determined for SLex bound
to E-, P-, and L-selectins are 0.72, 7.8, and 3.9 mM, respectively. For the
functional groups of E-selectin involved in SLex binding based on modeling,
see: (d) Kogan, T. P.; Revelle, B. M.; Tapp, S.; Scott, D.; Beck, P. J. A.
J. Biol. Chem. 1995, 270, 14047-14055.
In conclusion, this study describes the synthesis of several
new molecules that are structural and functional mimics of SLex
in selectin inhibition. It appears that very tight-binding inhibi-
tors, with an increase in binding energy of ∼6 kcal/mol (it is
noted that IC50 values do not always correspond to binding
energy), can be developed via incorporation of one or two new
groups to the carbohydrate mimic to have additional electrostatic
and/or hydrophobic interactions with the receptor. Work is in
(6) DeFrees, S. A.; Phillips, L.; Guo, L.; Zalipsky, S. J. Am. Chem. Soc.
1996, 118, 1601-1604. Spevak, W.; Foxall, C.; Carych, D. H.; Dasgupta,
F.; Nagy, J. O. J. Med. Chem. 1996, 39, 1018-1020. Also see ref 1b and
citations therein.
(7) Determined in a cell-free assay: Weitz-Schmidt, G.; Stokmaier, D.;
Scheel, G.; Nifantev, N. E.; Tuzikou, A. B.; Bovin, A. B. Anal. Biochem.
1996, 238, 184-190.
(8) When the long-chain hydrophobic group was changed to aryl
hydrophobic group, it was also shown a better activity than that of SLex
(unpublished result).
(9) Hung, S.-C; Lin, C.-C.; Wong, C.-H. Tetrahedron Lett. 1997, in press.
(10) Both fuculose 1-phosphate and rhamnulose 1-phosphate aldolases
were used to prepare the O-linked diastereomers.

8154 J. Am. Chem. Soc., Vol. 119, No. 35, 1997
Wong et al.
Scheme 2a
Scheme 4a
a Reagents and conditions: (a) FDP aldolase (200 U), pH ) 6.7, 30
h, 25 °C; (b) O3/78 °C, DMS/23 °C.
Cl2 (10 mL) and the resulting solution was quenched by
saturated NaHCO3. The aqueous layer was extracted with CH2-
Cl2 (2 × 10 mL), and the combined organic layers were washed
with brine, dried with MgSO4, filtered, evaporated, and purified
by column chromatography to provide acetate 8 in 83% yield:
1H NMR (500 MHz, CDCl3) δ 7.35-7.28 (m, 15 H), 5.72 (ddt,
J ) 17.0, 10.3, 6.9 Hz, 1 H), 5.04-5.00 (m, 2 H), 4.75 (d, J )
11.2 Hz, 1 H), 4.63-4.53 (m, 5 H), 4.39 (dd, J ) 11.6, 6.4 Hz,
1 H), 4.25 (dd, J ) 11.6, 2.8 Hz, 1 H), 4.07 (ddd, J ) 10.5,
5.9, 2.2 Hz, 1 H), 3.83-3.75 (m, 3 H), 3.62 (dd, J ) 4.4, 2.7
Hz, 1 H), 2.38-2.27 (m, 2 H), 2.05 (s, 3 H); 13C NMR (125
MHz, CDCl3) δ 170.90, 138.07, 137.92, 133.94, 128.43, 128.39,
128.31, 127.99, 127.95, 127.87, 127.83, 127.77, 127.67, 117.27,
76.93, 74.94, 74.73, 73.98, 72.25, 72.12, 72.02, 71.51, 63.20,
34.32, 20.90; HRMS (FAB, M + Cs) calcd for C32H36O6Cs
649.1566, found 649.1589.
3-(6-O-Hexadecanyl-2,3,4-tri-O-benzyl-r-D-mannopyrano-
syl)propene (9b). To a solution of 8 (516 mg, 1 mmol) in
anhydrous MeOH (5 mL) was added NaOMe (16.2 mg, 0.3
mmol) at 25 °C under argon. After 2 h, the mixture was
neutralized with Dowex 50 × 8-100 acidic resin and the
solution was filtered, washed with MeOH, and evaporated to
a Reagents and conditions: (a) O3/78 °C, DMS/23 °C, Jones reagent/0
°C; (b) EDC/HOBt (1.2 equiv), NMM, 0 °C; (c) H2, Pd-C (Degussa
type, 10% w/w), HOAc-H2O (8:2 v/v); (d) i. OsO4, NMO; ii. NaIO4,
iii. Jones reagent.
1
yield the desired alcohol compound (450.2 mg, 95%): H NMR
(400 MHz, CDCl3) δ 7.37-7.28 (m, 15 H), 5.68 (ddt, J ) 17.2,
10.2, 7.0 Hz, 1 H), 5.05-4.98 (m, 2 H), 4.83 (d, J ) 11.1 Hz,
1 H), 4.67-4.56 (m, 5 H), 4.03 (ddd, J ) 9.0, 6.3, 3.1 Hz, 1
H), 3.85 (t, J ) 8.0 Hz, 1 H), 3.81 (dd, J ) 11.6, 6.1 Hz, 1 H),
3.78 (dd, J ) 8.0, 3.1 Hz, 1 H), 3.72 (dd, J ) 11.6, 3.1 Hz, 1
H), 3.64 (t, J ) 3.1 Hz, 1 H), 3.61 (ddd, J ) 8.0, 6.1, 3.1 Hz,
1 H), 2.36 (ddd, J ) 14.8, 9.0, 7.0 Hz, 1 H), 2.22 (ddd, J )
14.8, 7.0, 6.3 Hz, 1 H), 2.1 (bs, 1 H); 13C NMR (100 MHz,
CDCl3) δ 138.12, 138.05, 133.79, 128.43, 128.39, 128.33,
128.00, 127.97, 127.81, 127.74, 127.69, 117.60, 77.93, 75.18,
74.51, 73.84, 73.46, 72.16, 71.91, 62.15, 34.11; HRMS (FAB,
M + Na) calcd for C30H34O5Na 497.2304, found 497.2315.
To a solution of above compound (1.00 g, 2.11 mmol) in
DMF (7 mL) was added 95% NaH (0.10 g, 2.74 mmol) at 0 °C
under argon. After 30 min, to the mixture was added 1-bro-
mohexadecane (0.84 mL, 2.74 mmol) followed by tetra-n-
butylammonium iodide (37.4 mg, 0.11 mmol) and the resulting
solution was warmed up to 25 °C overnight. The reaction was
quenched by H2O (10 mL), then extracted with EtOAc (3 × 10
mL), and the combined organic layers were washed with brine,
dried with MgSO4, filtered, evaporated, and purified by column
chromatography (hexane to EtOAc/hexane ) 1/20) to yield ether
9b (1.13 g, 77%). 1H NMR (400 MHz, CDCl3) δ 7.36-7.27
(m, 15 H), 5.79-5.68 (m, 1 H), 5.02-4.98 (m, 2 H), 4.74 (d,
J ) 11.4 Hz, 1 H), 4.61-4.54 (m, 5 H), 4.05 (dt, J ) 7.5, 4.8
Hz, 1 H), 3.86 (t, J ) 6.9 Hz, 1 H), 3.79-3.75 (m, 2 H), 3.71-
3.63 (m, 2 H), 3.61 (dd, J ) 4.5, 3.2 Hz, 1 H), 3.48-3.38 (m,
2 H), 2.39-2.26 (m, 2 H), 1.58-1.52 (m, 2 H), 1.25 (bs, 26
Scheme 3a
a Reagents and conditions: (a) EDC/HOBt (1.2 equiv), NMM, 0
°C, 63%; (b) LiOH, 87%; (c) H2, Pd-C (Degussa type, 10 % w/w),
HOAc-H2O (8:2 v/v), 91%.
progress to investigate the mechanisms of these mimics binding
and to prepare polyvalent inhibitors to further enhance the
inhibition.
Experimental Section
3-(6-O-Acetyl-2,3,4-tri-O-benzyl-r-D-mannopyranosyl)pro-
pene (8). To a solution of methyl 2,3,4,6-tetra-O-benzyl-R-
glycoside (7) (0.69 mmol) in CH3CN (1.4 mL) was added
allyltrimethylsilane (1.45 mmol) at 0 °C under argon. To the
mixture was added TMSOTf (0.35 mmol), and the reaction was
kept stirring under the same temperature overnight, then warmed
up to 25 °C. The mixture was added acetic anhydride (1 mL)
drop by drop. After 5 min, the reaction was diluted with CH2-

Mimics of Sialyl Lewis X in Selectin Inhibition
J. Am. Chem. Soc., Vol. 119, No. 35, 1997 8155
H), 0.88 (t, J ) 6.5 Hz, 3 H); 13C NMR (100 MHz, CDCl3) δ
138.36, 138.19, 138.13, 134.27, 128.34, 128.31, 128.27, 128.24,
127.97, 127.90, 127.84, 127.64, 127.56, 117.08, 76.84, 75.01,
74.82, 73.81, 73.46, 72.24, 71.93, 71.57, 71.36, 69.67, 34.55,
31.88, 29.65, 29.61, 29.51, 29.32, 26.13, 22.65, 14.09; HRMS
(FAB, M + Cs) calcd for C46H66O5Cs 831.3965, found
831.3984.
EtOAc/hexane), giving the product in low yield (35%): 1H
NMR (CDCl3, 400 MHz) δ 7.60-7.25 (m, 5 H), 6.02-5.92
(m, 1 H), 5.55 (s, 1 H), 5.33 (m, 1 H), 5.22 (m, 1 H), 4.36 (dd,
J ) 1.5, 12.4 Hz, 1 H), 4.27 (d, 1 H), 4.26 (m, 1 H), 4.22 (m,
1 H), 4.09 (dd, J ) 1.9, 12.4 Hz, 1 H), 3.95 (ddd, J ) 1.8, 7.7,
9.7 Hz, 1 H), 3.59 (s, 3 H), 3.48 (dd, J ) 3.6, 9.7 Hz, 1 H),
3.43 (m, 1 H); 13C NMR (CDCl3, 100 MHz) δ 138.56, 135.60,
129.66, 128.81, 127.12, 118.45, 104.48, 101.68, 79.42, 73.41,
70.99, 70.32, 69.71, 67.02, 57.33; IR (neat) 3419, 2966, 2871,
1450, 1401, 1370, 1079, 1050, 812 cm-1; HRMS calcd for
C17H22O6Na (M + Na) 345.1314, found 345.1316. Anal. Calcd
for C17H22O6: C, 63.34; H, 6.87. Found: C, 63.20; H, 6.85.
trans-1-(2,3,4,6-Tetra-O-benzyl-r-D-mannopyranosyl)pro-
pene (10). To a solution of the terminal olefin 9a (500 mg,
0.887 mmol) in benzene (50 mL) was added PdCl2 (catalytic),
and the solution was heated to reflux for 24 h. The reaction
mixture was filtered through Celite and evaporated, and the
crude oil was purified by silica gel chromatography (EtOAc:
hexane, 1:9 to 1:1), giving the internal olefin 10 in 46% yield
(30 mg): 13C NMR (CDCl3, 100 MHz) δ 138.34, 138.29,
138.26, 129.66, 128.27, 128.25, 127.92, 127.87, 127.74, 127.57,
127.50, 127.39, 126.90, 78.60, 76.03, 75.20, 74.50, 73.88, 73.59,
73.27, 91.99, 71.56, 69.42, 18.07; HRMS calcd for C37H40O5-
Cs (M + Cs), 697.1930, found 697.1954.
1-(2,3,4,6-Tetra-O-benzyl-r-D-mannopyranosyl)formic Acid
(11). To a solution of olefin 10 (230 mg, 0.407 mmol) in CH2-
Cl2 (20 mL) at -78 °C was bubbled O3 until a blue color
persisted. To remove residual O3, pure O2 was bubbled through
until the solution turned clear. DMS (1.0 mL) was added, and
the reaction mixture was warmed to 23 °C and stirred for 24 h.
The reaction mixture was concentrated under reduced pressure.
The crude oil was used directly without further purification.
To a solution of (COCl)2 (209 µL, 2.40 mmol) in CH2Cl2 (4
mL) at -78 °C was added DMSO (341 µL, 78.1 mmol). The
reaction mixture was warmed to 0 °C for 5 min and then
recooled to -78 °C. Methyl 3-allyl-4,6-benzylidene-2-hydroxy-
â-D-galactopyranoside (704 mg, 2.19 mmol) was dissolved in
CH2Cl2 (4 mL) and added slowly dropwise. The reaction
mixture was stirred for 30 min, and DIPEA was added (1.48
mL, 10.9 mmol). The reaction mixture was warmed to 23 °C,
diluted with CH2Cl2 (100 mL), washed with saturated NaHCO3
(50 mL), and dried (MgSO4). The crude product was used
directly in the next step without further purification.
To a solution of the above ketone in MeOH (20 mL) was
added NH4OAc until the solution was saturated. Sodium
cyanoborohydride (116 mg, 2.19 mmol) was added, and the
reaction mixture was stirred for 48 h. The reaction mixture
was partitioned between EtOAc (100 mL) and saturated
NaHCO3 (50 mL), and the aqueous layer was further extracted
with EtOAc (2 × 50 mL). The combined organic layers were
dried (MgSO4), concentrated under reduced pressure, and
chromatographed (5% MeOH/CH2Cl2), giving the amine 12 in
good yield (77% two steps): 1H NMR (CDCl3, 400 MHz) δ
7.66-7.25 (m, 5 H), 5.99-5.88 (m, 1 H), 5.46 (s, 1 H), 5.32-
5.26 (m, 1 H), 5.21-5.18 (m, 1 H), 4.36 (dd, J ) 1.4, 12.5 Hz,
1 H), 4.25 (d, J ) 1.4 Hz, 1 H), 4.20 (d, J ) 3.8 Hz, 1 H),
4.21-4.07 (m, 1 H), 4.08 (dd, J ) 2.0, 12.5 Hz, 1 H) 3.54 (s,
3 H), 3.54-3.48 (m, 1 H), 3.29 (d, J ) 1.3 Hz, 1 H), 3.21 (d,
J ) 4.0 Hz, 1 H), 2.19 (s, 1 H); 13C NMR (CDCl3, 100 MHz)
δ 138.41, 135.42, 129.71, 128.90, 127.0, 118.67, 103.01, 101,-
97, 75.67, 73.76, 69.93, 69.51, 67.41, 57.22, 51.86; IR (neat)
3376, 3310, 2867, 1748, 1687, 1587, 1542, 1451, 1402, 1366
cm-1; HRMS calcd for C17H24O5NNa (M + Na) 344.11474,
found 345.1476.
The aldehyde prepared above was dissolved in acetone (5
mL) and cooled to 0 °C. Jones reagent was added dropwise
until an orange color persisted. iPrOH (1 mL) was added to
quench any excess Jones reagent, and the reaction mixture was
then partitioned between EtOAc (50 mL) and 1 N HCl (50 mL).
The aqueous layer was extracted with EtOAc (50 mL), and the
combined organic phases were dried (MgSO4), concentrated
under reduced pressure, and purified by silica gel flash chro-
matography (EtOAc:Hexane:HOAc, 3:1:0.01), giving the car-
boxylic acid 11 in 70% yield (two steps, 634 mg): HRMS calcd
for C35H36O7Cs (M + Cs) 701.1515, found 701.1528.
Methyl 3-Allyl-2-amino-4,6-benzylidene-â-D-talopyrano-
side (12). To a solution of methyl â-D-galactopyranoside (10
g, 51.5 mmol) in CH3CN (250 mL) was added benzaldehyde
dimethyl acetal (15.6 mL, 103 mmol) followed by CSA (1.19
g, 5.15 mmol). After 30 min, Et3N (1 mL) was added and the
solvent was removed under reduced pressure and the crude solid
was recrystallized from hot MeOH, affording the benzylidene
acetal in good yield (85%): 1H NMR (CDCl3, 400 MHz) δ
7.55-7.35 (m, 5 H), 5.57 (s, 1 H), 4.36 (dd, J ) 1.4, 12.4 Hz,
1 H), 4.23 (dd, J ) 1.2, 3.8 Hz, 1 H), 4.22 (d, J ) 7.4 Hz, 1
H), 4.10 (dd, J ) 1.9, 12.5 Hz, 1 H), 3.60 (s, 3 H), 3.78-3.67
(m, 2 H), 3.51 (dd, J ) 1.6, 3.0 Hz, 1 H), 3.49 (d, J ) 5.48 Hz,
1 H); 13C NMR (CDCl3, 100 MHz) δ 138.0, 130.03, 129.0,
127.15, 104.38, 102.06, 75.75, 73.14, 72.18, 69.53, 67.06, 57.54;
IR (neat) 3385 (br), 2966, 2872, 1466, 1551, 1403, 1366, 1173,
1078 cm-1; MS calcd for C14H18O6Na (M + Na) 305.
To a solution of the above galactose benzylidene acetal (4.7
g, 16.7 mmol) in toluene (55 mL) was added Bu2SnO (4.56 g,
18.3 mmol), and the solution was dehydrated using a Dean-
Stark trap (130 °C, 2 h). The reaction mixture was cooled to
70 °C, and TBAI (4.3 g, 11.7 mmol) was added followed by
allyl bromide (2.18 mL, 25 mmol). The solution was stirred at
130 °C for 24 h before being cooled to 23 °C and partitioned
between EtOAc (200 mL) and saturated NaHCO3 (200 mL).
The aqueous layer was extracted with EtOAc (2 × vol), and
the combined organic layers were dried (MgSO4), concentrated
under reduced pressure, and chromatographed (1:1 to 100%
Methyl 2-[N-[(2,3,4,6-Tetra-O-benzyl-r-D-mannopyrano-
syl)carbonyl]amino-3-allyl-4,6-O-dibenzylidinetalopyrano-
side (13). To a solution of compound 12 (65 mg, 0.203 mmol),
mannose carboxylic acid 11 (150 mg, 0.264 mmol), NMM (45
µL, 0.407), and HOBt (41.1 mg, 0.305 mmol) in CH2Cl2 (3
mL) at 0 °C was added EDC (60.1 mg, 0.305 mmol). The
reaction mixture was warmed to 23 °C and stirred for 24 h.
The reaction mixture was diluted with EtOAc (50 mL) and
washed successively with a 5% citric acid solution (20 mL)
and saturated NaHCO3 (20 mL). The solvent was removed
under reduced pressure and dried (MgSO4), and the crude oil
was purified by silica gel chromatography (EtOAc:hexane, 1:3
to 3:1), giving the coupled product 13 in good yield (63%, 41
mg): 1H NMR (CDCl3, 400 MHz) δ 7.62-7.08 (m, 25 H),
5.85-5.70 (m, 1 H), 5.50 (s, 1 H), 5.16 (dd, J ) 1.3, 17.2 Hz,
1 H), 4.97 (dd, J ) 0.72, 9.6 Hz, 1 H), 4.88-4.27 (m, 4 H),
4.22 (d, J ) 3.2 Hz, 1 H), 4.16 (t, J ) 9.6 Hz, 1 H), 4.09 (dd,
J ) 1.6, 12.5 Hz, 1 H), 4.00-3.93 (m, 1 H), 3.84-3.75 (m, 3
H), 3.64-3.51 (m, 6 H), 3.40 (dd, J ) 2.5, 11.4 Hz, 1 H), 3.32
(s, 1 H), 2.64 (dd, J ) 1.2, 11.2 Hz, 1 H); HRMS calcd for
C52H57O11NCs (M + Cs) 1004.2986, found 1004.2951.

8156 J. Am. Chem. Soc., Vol. 119, No. 35, 1997
Wong et al.
Methyl 2-[N-[(2,3,4,6-Hydroxy-r-D-mannopyranosyl)car-
bonyl]amino]-3-carboxymethyl-4,6-hydroxytalopyranoside (1).
To a solution of olefin 13 (100 mg, 0.114 mmol) in CH2Cl2
(10 mL) at -78 °C was bubbled O3 until a blue color persisted.
To remove residual O3, pure O2 was bubbled through until the
solution turned clear. DMS (1.0 mL) was added, and the
reaction mixture was warmed to 23 °C and stirred for 4 h. The
reaction mixture concentrated under reduced pressure. The
crude oil was used directly without further purification.
1453, 1437, 1363, 1266, 1156, 1119 cm-1; HRMS calcd for
C36H38O7Cs (M + Cs) 715.1672, found 715.1680. Anal. Calcd
for C36H38O7: C, 74.20; H, 6.78. Found: C, 74.01; H, 6.50.
Dibenzyl N-[(2,3,4,6-Tetra-O-benzyl-r-D-mannopyrano-
syl)acetyl]-L-glutamate (16). To a solution of carboxylic acid
14 (50 mg, 0.086 mmol), H-Glu-(OBn)2‚pTsOH (0.095 mmol),
HOBt (12.8 mg, 0.095 mmol), and NMM (10.3 µL, 0.095 mmol)
in CH2Cl2 (500 µL) at 0 °C was added EDC (18 mg, 0.095
mmol). The reaction was allowed to stir for 24 h before being
diluted with CH2Cl2 (50 mL) and washed successively with a
5% citric acid solution (25 mL), saturated NaHCO3 solution
(25 mL), and brine (25 mL). The organic phase was dried
(MgSO4), concentrated under reduced pressure, and purified by
silica gel chromatography (EtOAc:hexane, 1:1), giving the
coupled product 16 in good yield (80%): 1H NMR (CDCl3,
400 MHz) δ 7.35-7.15 (m, 35 H), 5.10 (s, 2 H), 5.03 (m, 2
H), 4.60 (ddd, J ) 5.3, 8.3, 10.8 Hz, 1H), 4.51-4.35 (m, 8 H),
4.29 (ddd, J ) 3.1, 8.7, 8.7 Hz, 1 H), 4.04-3.98 (m, 1 H), 3.84
(dd, J ) 7.9, 10.2 Hz, 1 H), 3.72 (dd, J ) 3.0, 5.1 Hz, 1 H),
3.63 (dd, J ) 3.7, 5.2 Hz, 1H), 3.57 (dd, J ) 3.0, 7.1 Hz, 1 H),
3.55 (dd, J ) 4.7, 10.2 Hz, 1 H), 2.60 (dd, J ) 3.3, 16.0 Hz, 1
H), 2.52 (dd, J ) 9.0, 15.9 Hz, 1 H), 2.40-2.25 (m, 2 H), 2.16-
2.07 (m, 1 H), 1.90-1.81 (m, 1 H); 13C NMR (CDCl3, 400
MHz) δ 171.36, 170.66, 138.07, 137.88, 137.78, 137.71, 130.32,
128.54, 128.47, 128.45, 128.39, 128.35, 128.32, 128.18, 128.14,
128.09, 128.04, 127.97, 127.94, 127.85, 127.78, 127.63, 75.25,
72.31, 74.24, 73.13, 72.80, 72.47, 71.46, 67.97, 67.73, 66.98,
53.45, 37.22, 36.73; IR (neat) 3336, 3062, 3029, 2919, 2861,
1741, 165, 1515, 1453, 1208, 1096 cm-1; HRMS calcd for
C55H58O10N (M + H) 892.4061, found 892.4095.
N-[(r-D-Mannopyranosyl)acetyl]-L-glutamic Acid (2). To
a solution of the benzyl-protected glycine aminoglycoside 16
(33 mg, 0.045 mmol) in 80% HOAc/H2O was added a catalytic
amount of Pd/C (Degussa type, 10% by weight). The solution
was flushed with hydrogen for 30 min then stirred for 24 h
under a H2 atmosphere. The reaction mixture was filtered and
evaporated down under reduced pressure. The crude oil was
further evaporated with H2O (2 × 5 mL) and finally lyophilized,
giving mimic 2 as a white hygroscopic solid 990% yield): 1H
NMR (D2O, 400 MHz) δ 4.37-4.42 (m, 1 H), 4.32 (ddd, J )
1.8, 5.0, 5.0 Hz, 1 H), 3.87 (t, J ) 2.9 Hz, 1 H), 3.79 (dd, J )
3.3, 9.0 Hz, 1 H), 3.71-3.77 (m, 2 H), 3.67 (dd, J ) 9.2, 9.2
Hz, 1 H), 3.53-3.60 (m, 1 H), 2.80 (dd, J ) 10.8, 14.8 Hz, 1
H), 2.55 (dd, J ) 5.1, 14.9 Hz, 1 H), 2.46 (dd, J ) 7.0, 7.0 Hz,
2H), 2.11-2.20 (m, 1 H), 1.90-2.02 (m, 1 H); 13C NMR (D2O/
DMSO, 100 MHz) δ 192, 187, 181.8, 84.2, 83.7, 79.9, 76.2,
70.0, 44.3, 35.1; HRMS calcd for C13H22O10N (M + H),
352.1244, found 352.1238.
The aldehyde prepared above was dissolved in acetone (5
mL) and cooled to 0 °C. Jones reagent was added dropwise
until a orange color persisted. iPrOH (1 mL) was added to
quench any excess Jones reagent, and the reaction mixture was
then partitioned between EtOAc (50 mL) and 1 N HCl (50 mL).
The aqueous layer was extracted with EtOAc (50 mL), and the
combined organic phases were dried (MgSO4), concentrated
under reduced pressure, and purified by silica gel flash chro-
matography (EtOAc:HOAc, 95:5), giving the carboxylic acid
1
in 33% yield (two steps, 634 mg): H NMR (CDCl3, 400 MHz)
δ 7.54-7.10 (m, 25 H), 5.48 (s, 1 H), 4.77-4.26 (m, 5 H),
4.09-3.93 (m, 3 H), 3.94 (d, J ) 9.6 Hz, 1 H), 3.77 (s, 1 H),
3.64 (d, J ) 7.2 Hz, 1 H), 3.53 (s, 3 H), 3.57-3.47 (m, 1 H),
3.31 (s, 1 H), 2.64 (d, J ) 8.4 Hz, 1 H), 2.78 (d, J ) 8.4 Hz,
1 H); HRMS calcd for C51H55O13 NCs (M + Cs) 1022.2728,
found 1022.2768.
To a solution of the above protected mimic (33 mg, 0.037
mmol) in 80% HOAc/H2O (10 mL) was added a catalytic
amount of Pd/C (Degussa type, 10% by wt). The solution was
flushed with hydrogen for 30 min, then stirred for 24 h under
a H2 atmosphere. The reaction mixture was filtered through
Celite and evaporated down under reduced pressure. The crude
oil was further evaporated with H2O (2 × 15 mL) and finally
lyophilized, giving mimic 1 as a white hygroscopic solid: 1H
NMR (D2O, 400 MHz) δ 8.02 (d, J ) 7.6 Hz, 1 H), 4.58 (s, 2
H), 4.51 (s, 1 H), 4.48 (s, 1 H), 4.24-4.16 (m, 2 H), 4.07 (s, 1
H), 3.84-3.73 (m, 6 H), 3.62 (dd, J ) 3.2, 4.0 Hz, 1 H), 3.55-
3.45 (m, 5 H).
2-(2,3,4,6-Tetra-O-benzyl-r-D-mannopyranosyl)acetic Acid
(14). To a solution of olefin 9a (679 mg, 1.20 mmol) in CH2-
Cl2:MeOH (8 mL:4 mL) at -78 °C was bubbled O3 in O2 until
a blue color persisted. To remove residual O3, pure O2 was
bubbled through until the solution turned clear. DMS (1.7 mL,
24.0 mmol) was added, and the reaction mixture was warmed
to 23 °C and stirred for 24 h. The reaction mixture was
evaporated and partitioned between a saturated NaHCO3 solution
(50 mL) and EtOAc (5 mL). The aqueous phase was extracted
with EtOAc (2 × 30 mL), and the combined organic phases
were dried and concentrated under reduced pressure. The crude
oil was used directly without further purification.
Dibenzyl N-[(6-O-Hexadecanyl-2,3,4-tri-O-benzyl-r-D-
mannopyranosyl)acetyl]-L-glutamate (18). To a solution of
9b (1.13g, 1.62 mmol) in 1/1 acetone/H2O (10 mL) was added
NMO (0.24 g, 2.05 mmol) followed by a solution of OsO4 in
tBuOH (0.2 g, 2.5% w/w) at 25 °C. The solution was stirred
for 16 h, and the reaction was quenched by the addition of
Na2S2O3 (0.2 g), Florisil (1 g), and H2O (10 mL). The mixture
was acidified to pH ) 1 with 1 N HCl, and the resulting solution
was extracted with EtOAc (3 × 20 mL). The combined organic
layers were washed with saturated NaHCO3 and brine, dried
with MgSO4, filtered, and evaporated to yield a 1/1 mixture of
diastereomeric diols (1.2173 g).
The aldehyde prepared above was dissolved in acetone (5
mL) and cooled to 0 °C. Jones reagent was added dropwise
until a orange color persisted, which indicated the oxidation
had gone to completion. iPrOH (1 mL) was added to quench
any excess Jones reagent, and the reaction mixture was then
partitioned between EtOAc (50 mL) and 1 N HCl (50 mL).
The aqueous layer was extracted with EtOAc (50 mL), and the
combined organic phases were dried (MgSO4), concentrated
under reduced pressure, and purified by silica gel flash chro-
matography (EtOAc:hexane:HOAc, 3:1:0.01), giving the car-
boxylic acid 14 in excellent yield (90%, 634 mg): 1H NMR
(CDCl3, 400 MHz) δ 7.35-7.15 (m, 25 H), 4.02 (m, 1 H), 3.86
(dd, J ) 7.3, 10.0 Hz, 1 H), 3.78 (dd, J ) 2.7, 4.9 Hz, 1 H),
3.72 (dd, J ) 3.2, 3.2 Hz, 1 H), 3.66-3.62 (m, 1 H), 3.61 (dd,
J ) 2.8, 7.6 Hz, 1 H), 2.77 (dd, J ) 4.2, 15.8 Hz, 1 H), 2.55
(dd, J ) 8.7, 15.8 Hz, 1 H); IR (neat) 3059, 2866, 1719, 1496,
To a solution of above diols (1.2173 g) in THF (8 mL) was
added NaIO4 (0.61 g) in one portion. The stirred slurry was
added H2O (8 mL) over 5 min, and the mixture was kept stirring
for 2 h. The resulting solution was extracted with EtOAc (3 ×
20 mL), and the combined organic layers were washed with

Mimics of Sialyl Lewis X in Selectin Inhibition
J. Am. Chem. Soc., Vol. 119, No. 35, 1997 8157
brine, dried with MgSO4, filtered, and evaporated to yield the
crude aldehyde (1.1090 g).
(t, J ) 3.7 Hz, 1 H), 3.63 (dd, J ) 8.2, 2.9 Hz, 1 H), 3.59 (dd,
J ) 4.4, 3.2 Hz, 1 H), 3.41-3.38 (m, 1 H), 3.38 (t, J ) 6.9 Hz,
2 H), 2.79 (dd, J ) 16.0, 2.3 Hz, 1 H), 2.71 (dd, J ) 16.0, 9.5
Hz, 1 H), 1.39-1.36 (m, 2 H), 1.37 (t, J ) 7.1 Hz, 3 H), 1.26-
1.12 (m, 26 H), 0.88 (t, J ) 7.0 Hz, 3 H); 13C NMR (100 MHz,
CDCl3) δ 169.21, 166.25, 138.35, 137.69, 137.58, 137.44,
130.87, 128.64, 128.46, 128.42, 128.10, 127.90, 127.74, 124.90,
121.40, 75.39, 74.73, 74.55, 73.35, 72.80, 72.41, 71.77, 71.51,
67.75, 66.93, 60.88, 38.43, 31.86, 29.64, 29.60, 29.55, 29.49,
29.35, 29.31, 29.17, 25.82, 22.64, 14.27, 14.08; HRMS (FAB,
M + Cs) calcd for C54H73NO8Cs 996.4391, found 996.4353.
3-{N-[(6-O-Hexadecanyl-r-D-mannopyranosyl)]acetyl]-
amino}benzoic Acid (3a). An ice-cold solution of 0.25 M
LiOH in 75% MeOH(aq) (5.3 mL) was added to a solution of
19 (230 mg, 0.27 mmol) in tetrahydrofuran (5 mL), and the
mixture was vigorously stirred for 2 days at 4 °C. The resulting
solution was acidified with 1 N HCl to pH 1-2 and extracted
with EtOAc (3 × 10 mL). The combined organic layers were
washed with brine, dried with MgSO4, filtered, evaporated, and
purified by a short column chromatography to yield free acid
compound 193 mg (87%): 1H NMR (400 MHz, CDCl3) δ 9.19
(s, 1 H), 8.06 (t, J ) 1.7 Hz, 1 H), 8.02 (ddd, J ) 7.9, 1.7, 1.2
Hz, 1 H), 7.78 (dt, J ) 7.9, 1.2 Hz, 1 H), 7.37-7.23 (m, 16 H),
4.60 (d, J ) 12.0 Hz, 1 H), 4.57-4.49 (m, 5 H), 4.40 (dt, J )
8.8, 2.5 Hz, 1 H), 4.17 (dt, J ) 9.1, 3.4 Hz, 1 H), 4.00 (t, J )
9.9 Hz, 1 H), 3.81 (t, J ) 3.7 Hz, 1 H), 3.65 (dd, J ) 8.1, 2.9
Hz, 1 H), 3.61 (dd, J ) 4.5, 3.2 Hz, 1 H), 3.43-3.41 (m, 1 H),
3.39 (t, J ) 7.0 Hz, 2 H), 2.83 (dd, J ) 16.2, 2.5 Hz, 1 H),
2.70 (dd, J ) 16.2, 9.6 Hz, 1 H), 1.43-1.37 (m, 2 H), 1.31-
1.13 (m, 26 H), 0.87 (t, J ) 7.0 Hz, 3 H); 13C NMR (100 MHz,
CDCl3) δ 170.86, 169.36, 138.60, 137.68, 137.59, 137.39,
129.78, 128.89, 128.48, 128.45, 128.17, 127.95, 127.82, 127.79,
125.60, 125.43, 121.82, 75.41, 74.65, 74.46, 73.48, 72.74, 72.48,
71.81, 71.58, 67.83, 67.12, 38.64, 31.89, 29.68, 29.64, 29.60,
29.54, 29.41, 29.34, 29.20, 25.85, 22.66, 14.11; HRMS (FAB,
M + Cs) calcd for C52H69NO8Cs 968.4078, found 968.4060.
The above aldehyde (1.1090 g) was dissolved in acetone (7
mL), and the solution was cooled to 0 °C. The mixture was
added Celite (0.8 g) in one portion followed by the addition of
Jones reagent drop by drop until a orange color persisted, which
i
indicated the oxidation had gone to completion. PrOH (1 mL)
was added to quench any excess Jones reagent, and the reaction
mixture was then partitioned between EtOAc (50 mL) and 1 N
HCl (50 mL). The aqueous layer was extracted with EtOAc (2
× 50 mL), and the combined organic phases were dried with
(MgSO4), concentrated, and purified by silica gel flash chro-
matography (EtOAc/hexane/AcOH, 3/1/0.01) to yield the car-
boxylic acid 17 (0.904 g, 78% in three steps): HRMS (FAB,
M + Cs) calcd for C45H64O7Cs 849.3706, found 849.3729.
To a solution of carboxylic acid 17 (260 mg, 0.363 mmol)
in CH2Cl2 (3 mL) were added BnO-Glu(OBn)-NH2‚p-TsOH
(200 mg, 0.399 mmol), triethylamine (56 µL, 0.399 mmol),
HOBt (54.0 mg, 0.399 mmol), and EDC (76.4 mg, 0.399 mmol)
at 25 °C under argon. The reaction was allowed to stir for 24
h before being diluted with CH2Cl2 (20 mL) and washed
successively with a 1 N hydrochloric acid solution (15 mL),
saturated NaHCO3 solution (15 mL), and brine (15 mL). The
organic phase was dried with MgSO4, concentrated, and purified
by silica gel chromatography to yield 18 (271 mg, 73%): 1H
NMR (500 MHz, CDCl3) δ 7.33-7.22 (m, 25 H), 7.17 (d, J )
7.9 Hz, 1 H), 5.14 (s, 2 H), 5.07, 5.04 (ABq, J ) 12.3 Hz, 2
H), 4.66 (dt, J ) 7.9, 5.2 Hz, 1 H), 4.54-4.44 (m, 6 H), 4.29
(dt, J ) 8.3, 3.3 Hz, 1 H), 3.98-3.95 (m, 1 H), 3.78-3.71 (m,
3 H), 3.61-3.58 (m, 2 H), 3.39-3.29 (m, 2 H), 2.61 (dd, J )
15.8, 3.2 Hz, 1 H), 2.52 (dd, J ) 15.8, 8.7 Hz, 1 H), 2.43-
2.30 (m, 2 H), 2.23-2.16 (m, 1 H), 1.98-1.91 (m, 1 H), 1.49
(t, J ) 6.1 Hz, 2 H), 1.25 (bs, 26 H), 0.88 (dt, J ) 6.8, 2.7 Hz,
3 H); 13C NMR (100 MHz, CDCl3) δ 172.26, 171.35, 170.49,
137.81, 137.67, 135.70, 135.27, 128.46, 128.40, 128.32, 128.28,
128.22, 128.08, 128.04, 128.02, 127.78, 127.73, 127.69, 75.03,
74.27, 73.94, 73.89, 72.48, 72.28, 71.37, 68.31, 67.49, 66.90,
66.23, 51.37, 37.44, 31.82, 30.13, 29.61, 29.57, 29.45, 29.26,
27.02, 26.00, 22.59, 14.05; HRMS (FAB, M + Cs) calcd for
C64H83NO10Cs 1158.5071, found 1158.5116.
The above acid was hydrogenated by following the previously
1
described method to give compound 3a in 91% yield: H NMR
(400 MHz, CD3OD/CDCl3 ) 1/1) δ 8.16 (s, 1 H), 7.87 (d, J )
7.6 Hz, 1 H), 7.78 (d, J ) 7.6 Hz, 1 H), 7.40 (t, J ) 7.6 Hz, 1
H), 4.39-4.36 (m, 1 H), 4.10 (s, 1 H), 3.82-3.64 (m, 5 H),
3.47 (t, J ) 7.1 Hz, 2 H), 2.81 (dd, J ) 15.1, 9.9 Hz, 1 H),
2.67 (dd, J ) 15.1, 4.6 Hz, 1 H), 1.44-1.18 (m, 28 H), 0.89 (t,
J ) 6.8 Hz, 3 H); HRMS (FAB, M + Cs) calcd for C31H51-
NO8Cs 698.2669, found 698.2684.
N-[(6-O-Hexadecanyl-r-D-mannopyranosyl)acetyl]-L-
glutamic Acid (3). To a mixture of benzyl ether 18 (250 mg,
0.24 mmol) in HOAc/THF/H2O (12 mL, 4/1/1) was added a
catalytic amount of Pd/C (Degussa type, 10% by wt). The
solution was flushed with hydrogen for 30 min, then stirred for
24 h under a H2 atmosphere. The reaction mixture was filtered
and coevaporated with toluene under reduced pressure. The
crude produce was recrystallized from chloroform and hexane
to yield mimetic 3 as a white solid (130 mg, 93%): 1H NMR
(400 MHz, CD3OD/CDCl3, 1/1) δ 4.52-4.48 (m, 1 H), 4.30-
4.26 (m, 1 H), 3.76-3.69 (m, 6 H), 3.50 (t, J ) 7.0 Hz, 2 H),
2.67 (dd, J ) 14.9, 8.2 Hz, 1 H), 2.57 (dd, J ) 14.9, 5.8 Hz, 1
H), 2.44-2.40 (m, 2 H), 2.26-2.22 (m, 1 H), 2.05-1.98 (m, 1
H), 1.59-1.56 (m, 2 H), 1.27 (bs, 26 H), 0.89 (t, J ) 6.9 Hz,
3 H); HRMS (FAB, M + Na) calcd for C29H53NO10Na
598.3567, found 598.3576.
Compound 20. D-Mannose (1500 mg, 8.3 mmol) was added
to 10 mL of allyl alcohol together with a catalytic amount (10
mg) of camphorsulfonic acid. The mixture was heated to 90
°C overnight, and then the excess allyl alcohol was evaporated
in Vacuo. Flash chromatography of the residue (EtOAc:MeOH,
6:1 to 4:1) gave 1400 mg (76%) of R-O-allylmannopyrano-
side: 13C NMR (CD3OD, δ, ppm) 136.31, 118.28, 101.48,
75.47, 73.55, 72.94, 69.67, 69.36, 63.68.
To a solution of the above compound (482 mg, 2.2 mmol) in
CH2Cl2:MeOH (1:4) was bubbled ozone at -78 °C in the
presence of a catalytic amount of NaHCO3. After the blue color
appeared, indicating that the solution was saturated with ozone,
an excess (3 equiv) of Ph3P was added. After stirring overnight,
an extractive workup was performed (CH2Cl2/water), the
aqueous portion was evaporated, and the residue showed the
presence of only one aldehyde as the dihydrate as judged by
13C NMR (CD3OD, δ, ppm): 100.13, 88.22, 72.73, 70.36, 69.84,
66.66, 60.85.
Ethyl 3-{N-[(6-O-Hexadecanyl-2,3,4-tri-O-benzyl-r-D-
mannopyranosyl)acetyl]amino}benzoate (19). The prepara-
tion for the coupling of 17 and ethyl 3-aminobenzoate was
followed by the above procedure to afford 19 in 63% yield:
1H NMR (500 MHz, CDCl3) δ 9.09 (s, 1 H), 8.05 (t, J ) 1.5
Hz, 1 H), 7.84 (d, J ) 6.5 Hz, 1 H), 7.75 (dt, J ) 6.5, 1.5 Hz,
1 H), 7.34-7.22 (m, 16 H), 4.60 (d, J ) 12.1 Hz, 1 H), 4.56-
4.48 (m, 5 H), 4.39-4.35 (m, 1 H), 4.35 (q, J ) 7.1 Hz, 2 H),
4.16 (dt, J ) 9.0, 3.5 Hz, 1 H), 4.00 (t, J ) 10.0 Hz, 1 H), 3.80
Compound 20a. The ozonolysis of 9a was performed as
described above. The aldehyde product (2 mmol, 1.1 g) was

8158 J. Am. Chem. Soc., Vol. 119, No. 35, 1997
Wong et al.
-
dissolved in a 3:1 mixture of THF and water and hydrogenated
overnight at 1 atm in the presence of a catalytic amount of Pd-
C. After filtration through Celite and evaporation of the solvent,
the deprotected aldehyde 20a (440 mg, 98%) was isolated: 13C
NMR (D2O) major 88.36 (hydrate), 75.05, 74.13, 71.45, 70.68,
67.38, 61.30, 35.65 (CH2); minor 204.35 (aldehyde), 74.70,
72.38, 70.68, 70.49, 67.29, 60.99, 42.23 (CH2).
were further separated by ion exchange (HCO3 column, 400
mM of Et3NH‚HCO3), converted to the H+ form (Dowex-50
H+) and lyophilized to yield the product.
Compound 4: 1H NMR (D2O, 400 MHz) δ 4.72 (d, J ) 1.7
Hz, 1H), 4.69 (dd, J ) 18.4, 6.7 Hz, 1H), 4.54 (dd, J ) 18.4,
6.7 Hz, 1H), 4.41 (J ) 3 Hz, 1H), 4.15 (m, J ) 8.7, 5.7, 3 Hz,
1H), 3.83 (dd, J ) 3.3, 1.7 Hz, 1H), 3.75-3.65 (m, 3H, 3.60
(m, 2H), 3.55-3.45 (m, 2H) ppm; 13C NMR (D2O, 100 MHz)
δ 206.07, 96.49, 76.71, 73.72, 71.11, 70.94, 70.71, 69.18, 68.04,
65.71, 61.73 ppm.
Enzymatic Aldol Reaction. An aldehyde (1.2-1.5 mmol)
was dissolved in a solution of dihydroxyacetone phosphate
(DHAP, 1 mmol, 3 mL of a 330 mM solution). The pH was
adjusted to 6.7 by adding NaOH and 200 U of FDP aldolase
(Sigma) was added. The progress of the reaction was followed
by DHAP consumption (UV assay) and by 31P-NMR spectros-
copy. After DHAP had been consumed and 31P-NMR showed
the appearance of a new product, the pH was adjusted to 8 and
1 g of BaCl2‚2H2O (4.4 mmol) in 5 mL of water was added
slowly. The cloudy mixture was kept in an ice bath for 15
min, and the precipitates were removed by centrifugation. Two
volumes of acetone were added to the supernate and the mixture
stored at 0 °C for 1 h. The precipitates were collected by
centrifugation, and the supernatant was discarded. The pellet
was treated with Dowex-50 H+ until the solid was completely
dissolved (ca. 30 min), and the resin was filtered off. The pH
of the filtrate was adjusted to 7.0 by adding NaOH. Lyophiliza-
tion of the solution yielded a mixture of the phosphonates that
1
Compound 4a: H NMR (D2O, 400 MHz) δ 4.55 (dd, J )
18.7, 6 Hz, 1H), 4.45 (dd, J ) 18.7, 6, 1H), 4.33 (d, J ) 2 Hz,
1H), 4.28 (ddd, J-10.4, 3, 2 Hz, 1H), 4.20 (ddd, J ) 11.5, 3.6,
2 Hz, 1H), 3.77 (dd, J ) 3.3, 9.3 Hz, 1H), 3.74 (dd, J ) 12.1,
5.8 Hz, 1H), 3.67 (dd, J ) 9.3, 3.3 Hz, 1H), 3.56 (dd, J )
12.1, 5.8 Hz, 1H), 3.48 (t, J ) 9.3 Hz, 1H), 3.42 (ddd, J ) 9.3,
5.8, 2.2 Hz, 1H), 1.92 (ddd, J ) 14.7, 11.5, 3 Hz, 1H), 1.60
(ddd, J ) 14.7, 10.4, 3.6 Hz, 1H) ppm; 13C NMR (D2O, 100
MHz) δ 212.60, 78.13, 75.11, 73.97, 72.09, 70.86, 68.40, 68.20,
67.65, 61.47, 30.49 ppm.
Acknowledgment. This research was supported by the NSF
and Novartis Pharma AG.
JA970920Q