Generation of C-glycoside peptide ligands for cell surface carbohydrate receptors using a four-component condensation on solid support

Full text of DOI:10.1021/jo960119j

8
350
J . Org. Chem. 1996, 61, 8350-8354
Gen er a tion of C-Glycosid e P ep tid e Liga n d s
for Cell Su r fa ce Ca r boh yd r a te Recep tor s
Usin g a F ou r -Com p on en t Con d en sa tion on
Solid Su p p or t
Daniel P. Sutherlin, Todd M. Stark, Robert Hughes, and
Robert W. Armstrong*
Department of Chemistry and Biochemistry, University of
California at Los Angeles, Los Angeles, California 90095
Received J anuary 18, 1996
In tr od u ction
Interest in cell surface carbohydrates1 has steadily
increased over the past two decades as a result of the
cloning of numerous glycosylated receptors. These oli-
gosaccharides are known to play important roles in
adhesion events such as the recruitment of leukocytes
F igu r e 1.
Ba ck gr ou n d
2
3
in inflammation, metastasis, and recognition of cells by
viral4 and bacterial pathogens.5 The wide variety of
Cell surface carbohydrates themselves make poor drug
candidates due to their biological instability in the gut
and poor binding affinities to their receptors. Approaches
to circumvent these problems have included multivalent
ligands,10 the use of alternate frameworks to appropri-
biological functions involving carbohydrates makes in-
hibitors for the receptors that bind them attractive
therapeutic targets. In order to explore therapeutics
aimed at the general class of cell surface carbohydrate
1
1
ately position individual sugars, and the use of C-
glycosides.12 Our approach utilizes C-glycosides as the
carbohydrate-based component. These compounds are
resistant to both chemical and enzymatic hydrolysis and
do not stray from their O-glycosidic counterparts either
in binding affinity to natural ligands or in solution
conformation.13
receptors, we have applied the concepts of combinatorial
chemistry to carbohydrate drug discovery.6 Typical of
combinatorial chemistry approaches, a rapid and flexible
strategy that generates defined compounds with vari-
ability at different sites in the final structure would be
advantageous.
This note describes a combinatorial approach to the
synthesis of glycomimetic candidiates that bear a struc-
tural resemblance to cell surface carbohydrates. This
Experimental studies on the energetics of carbohydrate-
receptor binding has shed light on the contributing
1
4
7
8
factors involved in this important binding event. One
hypothesis involving carbohydrate-receptor binding con-
cludes that sugar hydroxyl groups contribute little to the
overall binding energy due to favorable solvation of the
ligand by water in solution and that hydrophobic interac-
tions can drive complexation. Thus, ligands presenting
a mix of mono or oligo C-saccharides that are required
for binding along with other nonpolar functionalities may
yield more potent sugar ligands. Glycomimetics which
have a peptide or non-peptide core structure serving as
a scaffold to display the external sugars have recently
been reported and have biological activities similar to
approach uses the Ugi four-component condensation,
performed on a solid support, to cluster C-glycosides and
other functionalities around a predictable core structure.
This solid phase methodology is demonstrated first
through the synthesis of eight fully deprotected monosac-
charides and disaccharides that can be targeted toward
a variety of cell surface carbohydrate receptors, high-
lighting the generality of the strategy. Second, with this
9
methodology in place, a 96-well, 192-compound focused
library of glycomimetics targeting the receptors of sialyl
Lewis x (NeuAcR2,3Galâ1,4(FucR1,3)GlcNAc, compound
1
, Figure 1) is discussed.
1
0c,f
that of their target blood group determinants.
As an
example, compounds 2 and 3 (Figure 1), designed to
mimic the biologically relevant oligosaccharide sialyl
Lewis x 1, have been reported and are inhibitors of
(
1) (a) Varki, A. Glycobiology 1993, 3, 97-130. (b) Feizi, T. Curr.
Opin. Struct. Bio. 1993, 3, 701. (c) Varki, A. Proc. Natl. Acad. Sci.
U.S.A. 1994, 91, 7390.
(
Aruffo, A.; Kolanus, W.; Polley, M. J .; Phillips, M. L.; Wagner, E.;
Nudelman, E.; Sinhal, A. K.; Hakomori, S.; Paulson, J . C. Proc. Natl.
Acad. Sci. U.S.A. 1991, 88, 6224.
2) (a) Butcher, E. C. Am. J . Path. 1990, 1, 3-11. (b) Walz, G.;
(10) (a) Kiessling, L. L.; Pohl, N. L. Chem. Biol. 1996, 3, 71. (b) Nagy,
J . O.; Wang, P.; Gilbert, J . H.; Schaefer, M. E.; Hill, T. G.; Callstrom,
M. R.; Bednarski, M. D. J . Med. Chem. 1992, 35, 4501-4502.
(11) (a) Armstrong, R. W.; Sutherlin, D. P.; Wolinski, L. Presented
at the 31st Annual ACS Western Regional Meeting, San Diego, CA,
October 18-21, 1995. (b) Rao, N. N. Presented at the 31st Annual ACS
Western Regional Meeting, San Diego, CA, October 18-21, 1995. (c)
Uchiyama, T.; Vassilev, V.; Kajimoto, T.; Wong, W.; Lin, C.-C.; Huang,
H.; Wong, C.-H. J . Am. Chem. Soc. 1995, 117, 5396. (d) Huryn, D.
Presented at the 31st Annual ACS Western Regional Meeting, San
Diego, CA, October 18-21, 1995. (e) For a review see Bertozzi, C. R.
Chem. Biol. 1995, 11, 703-708. (f) 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. 1995, 38, 4976-4984.
(12) (a) Postema, M. H. D. Tetrahedron 1992, 48, 8545-8599. (b)
Wei, A.; Haudrechy, A.; Audin, C.; J un, H.-S.; Haudrechy-Bretel, N.;
Kishi, Y. J . Org. Chem. 1995, 60, 2160.
(13) Wei, A.; Boy, K. M.; Kishi, Y. J . Am. Chem. Soc. 1995, 117,
9432-9436.
(14) Toone, E. J . Curr. Opin. Struct. Bio. 1994, 4, 719-728.
(
3) (a) Phillips, M. L.; Nudelman, E.; Gaeta, F. C. A.; Perez, M.;
Sinhal, A. K.; Hakomori, S.; Paulson, J . C. Science 1990, 250, 1130.
b) Higashi, H.; Hirabayashi, Y.; Fukui, Y.; Naiki, M.; Matsumoto, M.;
Ueda, S.; Kato, S. Cancer Res. 1985, 45, 3796-3802.
4) (a) Paulson, J . C. The Receptors; Academic: New York, 1985;
(
(
Vol. 2. (b) Wharton, S. A.; Weis, W.; Skehel, J . J .; Wiley, D. C. The
Influenza Virus; Plenum: New York, 1989.
(
5) (a) Gyler, M.; Rose, D.; Bundle, D. Science 1991, 253, 442. (b)
Boren, T.; Falk, P.; Roth, K. A.; Larson, G.; Normark, S. Science 1993,
62, 1892.
6) (a) Gallop, M. A.; Barrett, R. W.; Dower, W. J .; Fodor, S. P. A.;
2
(
Gordon, E. M. J . Med. Chem. 1994, 37, 1233-1251. (b) Gordon, E. M.;
Barrett, R. W.; Dower, W. J .; Fodor, S. P. A.; Gallop, M. A. J . Med.
Chem. 1994, 37, 1385-1401.
(
7) Ugi, I. Angew. Chem., Int. Ed. Engl. 1982, 21, 810-819.
(
8) (a) Ugi, I.; D o¨ mling, A.; H o¨ rl, W. Endeavour 1994, 18, 115-123.
(
b) Wipf, P.; Cunningham, A. Tetrahedron Lett. 1995, 36, 7819-7822.
(9) Each well contains two diastereomers.
S0022-3263(96)00119-3 CCC: $12.00 © 1996 American Chemical Society

Notes
J . Org. Chem., Vol. 61, No. 23, 1996 8351
Ta ble 1. Com p on en ts for Solid P h a se Rea ction sa
2 2
F igu r e 2. Reagents and conditions: (a) (i) MeOH/CH Cl , rt,
2
2 2
4 h; (ii) wash polymer; (b) 20% TFA in CH Cl .
E-selectin with relative binding potencies of 1.5 and 0.8,
respectively, in comparison to the IC50 of 1 mM for 5.
The Ugi reaction is a multiple component condensation
(MCC) reaction that combines an aldehyde, carboxylic
acid, isocyanide, and amine, resulting in R-acylamino
amide 4 (Figure 2). It allows the rapid generation of a
large number of compounds based on a common core
structure and displaying varied functionality. Research
in our laboratories has led to the adaptation of this
reaction to solid-support through the utilization of Rink15
resin as the amine component, yielding acylamino amide
5
upon removal from the polymer.16 By employing solid
support, the use of excess reagents to drive reactions to
completion and the elimination of chromatography allow
for the rapid generation of pure compounds in moderate
yield in a 96-well plate format easily adaptable to high
throughput screening.
Resu lts
Prior to performing a focused library of sialyl Lewis x
glycomimetics, a more general approach was taken to
investigate the behavior of protected carbohydrate com-
ponents in the Ugi reaction. This allowed for a general
understanding of expected yields, purities, and diaste-
reoselectivities that one would expect when moving to a
larger library format. One main issue to address was
the protection-deprotection scheme for the carbohy-
drates that would provide compounds of reasonable
purity and acceptable yield, eliminating the need for
chromatography.
a
The product corresponding to each entry results from the
condensation of the four components listed in each row. All
products are in the deprotected form except for entries 3 and 4.
Table 1 shows examples of the components that were
used in the preliminary Ugi reactions. The C-glycoside
components used were synthesized through standard
methods.17 The corresponding acids were obtained via
a buffered sodium chlorite oxidation of the aldehyde
precursors.18 Products of the reactions in Table 1 can
be identified by referring to the R-acylamino amide core
in Figure 1 and enlisting the appropriate components in
each entry. For example, the product for entry 4,
tripeptide 7 (Figure 3), is derived from a reaction with
Rink resin, methyl isocyanoacetate (MICA), N-FMOC-L-
phenylalanine, and the fucose aldehyde 6.19 This is a
F igu r e 3. Product from entry 4 in Table 1. Reagents and
conditions: (a) (i) MeOH/CH
lanine, MICA, and Rink resin amine; (ii) wash polymer; (b)
0% TFA in CH Cl
2 2
Cl , rt, 24 h, N-FMOC-phenyla-
2
2
2
.
(
15) Rink, H. Tetrahedron Lett. 1987, 28, 3787.
(16) (a) Armstrong, R. W.; Combs, A. P.; Tempest, P. A.; Brown, S.
D.; Keating, T. A. Acc. Chem. Res. 1996, 29, 123. (b) Tempest, P. A.;
Brown, S. D.; Armstrong, R. W. Angew. Chem., Int. Ed. Engl. 1996,
one-step synthesis of a tripeptide with a C-glycosylated
serine analog as the center amino acid.
20
3
5, 640. For other applications of the Ugi reaction in combinatorial
chemistry developed in the Armstrong group, see: (c) Keating, T. A.;
Armstrong, R. W. J . Am. Chem. Soc. 1995, 117, 7842. (d) Keating, T.
A.; Armstrong, R. W. J . Am. Chem. Soc. 1996, 118, 2574. (e) Strocker,
A. M.; Keating, T. A.; Tempest, P. A.; Armstrong, R. W. Tetrahedron
Lett. 1996, 37, 1149.
Compounds in Table 1 were obtained in fair to high
yields depending on the stoichiometry of the reacting
2
1
components relative to the Rink amine resin.
The
highest yield obtained was 71% in entry 5 when 3 equiv
of each sugar to 1 equiv of the resin bound amine was
(
17) (a) Hosomi, A.; Sakata, Y.; Sakurai, H. Tetrahedron Lett. 1984,
5, 2383. (b) Kraus, G. A.; Molina, M. T. J . Org. Chem. 1988, 53, 752.
c) Lewis, M. D.; Cha, J . K.; Kishi, Y. K. J . Am. Chem. Soc. 1982, 104,
976.
18) (a) Walborski, H. M.; Gawronska, K.; Gawronski, J . K. J . Am.
2
(
4
(
(20) Bertozzi, C. R.; Hoeprich, P. D. J r.; Bednarski, M. D. J . Org.
Chem. 1992, 57, 6092.
(21) Yields are as follows: entry 1, R ) Bn, 56%; R ) Ac, 77%; entry
2, 54%; entry 3, 33%; entry 4, 17%; entry 5, 71.5%; entry 6, 56%; entry
7, 65%; entry 8, 24%; entry 9, 53% yield.
Chem. Soc. 1987, 109, 6719. (b) Hillis, L. R.; Ronald, R. C. J . Org.
Chem. 1985, 50, 470.
(19) The synthesis of the glucose version of 3 is outlined in
Armstrong, R. W.; Sutherlin, D. P. Tetrahedron Lett. 1994, 35, 7743.

8
352 J . Org. Chem., Vol. 61, No. 23, 1996
Notes
used.22 When the equivalency of sugar is dropped to two,
the yields were consistently 50% ( 10%. We have
observed that in most cases the products are g95%
pure.23 The diastereoselectivity of these reactions ranged
from 4:1 in tetrabenzyl-â-C-galactoside found in entry 2
to 1:1 in entry 4 when the homologated tribenzyl-R-C-
fucoside was used. As a general rule, chiral aldehydes
have the greatest effect on the diastereoselecivity due to
the proximity they have to the newly formed stereocenter
while the sugar acids have little effect (approximately
Ta ble 2. Com bin a tor ia l Libr a r y Dir ected tow a r d Sia lyl
Lew is xa
1
:1 ratios of diastereomers). The R-substituted C-glyco-
sides induce little to no diastereoselectivity.
The generality of this strategy is demonstrated by the
diversity of products, including the disaccharide com-
pounds in entries 1 and 5, the fatty acid derivative in
entry 7, and the use of a diacid in entry 6 which, if the
MCC is performed in solution, would result in Ugi
reactions at both carboxyl termini. Should a biological
assay identify an active compound in the two diastere-
omer mix, the appropriate acylamino amide would need
to be synthesized through a more rigorous enantioselec-
tive synthesis or the diastereomers separated by chro-
matography in order to deconvolute the result. Many
alternatives exist for the synthesis of optically active
amino acids.24
a
Schematic representing the 96-compound library. Individual
wells contain a single reagent from each box, and all wells contain
the acetylated C-fucose as the aldehyde component.
Two strategies for the deprotection of the sugar hy-
droxyl protecting groups (benzyl and acetate) were
investigated. For both deprotection strategies, chroma-
tography was not needed. Because solution phase hy-
drogenation proceeds in high yields and with few side
reactions, the benzyl ethers could be removed efficiently
following TFA cleavage with H and Pd(OH) on carbon.
2 2
After filtration of the Pd catalyst, compounds of high
purity were observed.
important in the binding of sialyl Lewis x to E-selectin
and are intended to mimic the corresponding carboxylate
of N-acetylneuraminic acid along with the sugar. As
illustrated in compounds 2 and 3, provided that the three
hydroxyl residues of the fucose and the carboxylate are
retained and displayed to the receptor with the appropri-
ate conformation and distance from one another, com-
petitive binding can be observed.
19
Protocols for removal of protecting groups while the
compounds remained on the polymer were also developed.
Alternate homogeneous debenzylation methods suitable
We envisioned the synthesis of ligands that would vary
the distance from carboxylate to fucose using diacids of
increasing length and a fucose aldehyde in a solid phase
Ugi reaction. A MCC can, in addition to scanning this
distance requirement, probe the active site for other
favorable interactions by changing the amine and iso-
cyanide components. To do this the Rink polymer amine
component was coupled to five different N-FMOC amino
acids under DCC conditions, providing five different
amines after FMOC deprotection. Eight diacids of vari-
able lengths were chosen along with two isocyanides,
methyl isocyanoacetate (MICA) and benzyl isocyanide.
All reagents were added as 1 M solutions in 1 mL wells
containing 1 equiv of resin bound amine. Diacids were
dissolved in 1:1 MeOH/THF, a solvent system necessary
to obtain reasonable yields. Two and one-half equiva-
for solid phase either result in low yields or are not
compatible with the variety of functional groups used.25
However, acetylated C-glycosides are easy to synthesize
and are good candidates for deprotection on the polymer.
Deacetylation was achieved with 1 M NaOMe in a 1:1
MeOH/THF mixture to give completely deprotected com-
pounds that could then be cleaved from the polymer. We
found this on-polymer deprotection scheme to be the more
convenient of the two approaches; however, the benzy-
lated structures are useful alternatives that can be
employed for substrates that may be unstable to the basic
deacetylation conditions or in cases where orthogonal
protecting groups are desired.
We next turned our attention to the combinatorial
library of sialyl Lewis x blood group glycomimetics using
entry 6 in Table 1 as a model. Using the easily obtain-
able fucose aldehyde and a variety of components (Table
lents of the C-fucose as the aldehyde were added in CH
2
-
Cl , followed by 5.0 equiv of the isocyanide, 30 min later.
2
After 36 h the polymer was washed and treated with 1
mL of a 1 M NaOMe solution for 4 h. The compounds
were cleaved from the polymer with 2 mL of 20% TFA in
2
), 192 compounds were prepared. On the basis of
precedence, this core structure was an ideal starting point
for library generation. It is presently understood that
both the fucose and the carboxylate functionalities are
2 2
CH Cl
, rinsed with 0.5 mL of methanol,26 and dried in
a vacuum oven. All expected products were formed in
roughly 50% yield and in high purity except in those wells
containing the olefinic diacid where no product was
observed.27 This illustrates that this method can be used
for preparing large numbers of glycomimetics in a
preliminary screening program.
(22) In all cases the equivalency of the resisn bound amine was
determined by the loading level indicated by the manufacturer in
mmol/g.
(23) The product from entry 3 was found be 85% pure with excess
napthyl peaks in the NMR, most likely due to insufficient rinsing of
the pollymer suport.
(
24) Williams, R. M. Synthesis of Optically Active R-Amino Acids;
Pergamon Press: New York, Oxford, 1989.
25) Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic
Synthesis, 2nd ed.; Wiley-Interscience: New York, 1991.
(26) This caused some methyl ester formation of the free acid from
concentration of TFA and methanol. In subsequent experiments this
methanol wash was deleted from the procedure.
(

Notes
J . Org. Chem., Vol. 61, No. 23, 1996 8353
Con clu sion
added and extracted three times with equal portions of EtOAc.
The combined organic layers were dried with Na
evaporated to yield a clear oil.
2 4
SO and
The solid phase synthesis of glycomimetics has been
demonstrated. Central to this work is the solid phase
Ugi four-component condensation with a variety of func-
tionalized C-glycosides which can accommodate different
protecting group strategies. We feel this is a simple and
powerful way to achieve rapid diversity in libraries that
target carbohydrate receptor ligands. Assaying the
compounds in Table 2 should provide insight into binding
requirements for the sialyl Lewis x blood group tetrasac-
charide. However, compounds synthesized according to
this strategy are not limited to blood group determinants
but all cell surface carbohydrates. We are presently
working toward these goals as well as expanding the
scope of this process to other functionalized components
and carbohydrate clustering.
Tetr a a cetyl C-ga la ctose a cid : yield ) 95%. IR (neat): ν
max 2950, 2928, 2817, 2361, 1749, 1437, 1371, 1221, 1101, 1051,
9
)
1
-
1
1
52, 906, 800, 738 cm
.
H NMR (400 MHz): δ 5.41 (d, 1H, J
3.2 Hz), 5.11 (dd, 1H, J ) 9.8, 9.9 Hz), 5.03 (dd, 1H, J ) 3.3,
0.0 Hz), 4.20-4.07 (m, 2H), 4.04 (dd, 1H, J ) 6.6, 11.3Hz), 3.92
(
m, 1H), 2.61 (dd, 1H, 8.4, 16.1 Hz), 2.55 (dd, 1H, J ) 3.9, 16.1
13
Hz), 2.14 (s, 3H), 2.03 (s, 3H), 2.01 (s, 3H), 1.96 (s, 3H).
C
NMR: δ 174.8, 170.5, 170.3, 170.1, 169.9, 74.7, 74.2, 71.8, 68.8,
6
3
7.5, 61.3, 37.1, 20.6, 20.6, 20.6, 20.5. HRMS (EI): M + H calcd
91.1240, found 391.1231.
Tr ia cetyl C-fu cose a cid : yield >95%, crude was used in all
reactions. IR (neat): υ max 3476, 2988, 1747, 1373, 1227, 1059
-1
1
cm
.
H NMR (360 MHz): δ 8.16 (bs, 1H), 5.24 (dd, 1H, J )
5.7, 9.9 Hz), 5.15 (dd, 1H, J ) 2.1, 3.2 Hz), 5.06 (dd, 1H, J )
6.6, 9.9 Hz), 4.58 (m, 1H), 3.94 (m, 1H), 2.65 (dd, 1H, J ) 8.7,
1
3
5.4 Hz), 2.56 (dd, 1H, J ) 5.7, 15.4 Hz), 2.04 (s, 3H), 1.94 (s,
13
H), 1.89 (s, 3H), 1.03 (d, 3H, J ) 6.4 Hz).
C NMR (90.5
MHz): δ 174.5, 170.5, 170.0, 169.6, 70.1, 69.3, 68.1, 67.0, 66.5,
Exp er im en ta l Section
20.3, 15.4. HRMS (FAB): M + H calcd 333.1186, found
3
33.1197.
Gen er a l P r oced u r es. The procedures requiring anhydrous
conditions were the debenzylations and the preparation of the
Tetr a ben zyl C-ga la ctose a cid : yield > 95%, crude was used
in all reactions. IR (neat): ν max 3030, 2870, 1713, 1455, 1271,
1
M sodium methoxide. For these reactions, flame-dried flasks
-1
1
1
1
1
4
101 cm
. H NMR (360 MHz): δ 7.44-7.26 (m, 20H), 5.02 (d,
were used and an inert atmosphere of nitrogen was maintained.
Solvents were distilled immediately prior to use: THF from
sodium/benzophenone ketyl and methanol from magnesium
turnings. Anhydrous DMF was purchased from Aldrich and
used directly. For all other procedures reagent-grade solvents
are sufficient. Rink resin was purchased from Advanced
ChemTech. The loading level of the polymer was 0.56 mmol/g.
Thin layer chromatography was performed on silica gel with
precoated glass plates (E. Merck Brinkman, Kieselgel 60 F254,
H, J ) 11.1 Hz), 4.98 (d, 1H, J ) 11.6 Hz), 4.80 (d, 1H, J )
1.7 Hz), 4.70 (d, 1H, J ) 11.6 Hz), 4.68 (d, 1H, J ) 11.0 Hz),
.67 (d, 1H, J ) 11.6 Hz), 4.50 (d, 1H, J ) 11.7 Hz), 4.43 (d, 1H,
J ) 11.7 Hz), 4.06 (d, 1H, J ) 2.3 Hz), 3.8-3.6 (m, 6H), 2.84
13
(
dd, 1H, J ) 2.7, 16.0 Hz), 2.56 (dd, 1H, J ) 7.9, 15.8 Hz).
NMR (90.5 MHz): δ 176.1, 138.5, 138.0, 138.0, 137.7, 128-127
m, 12C), 84.5, 77.8, 77.1, 75.9, 75.2, 74.5, 73.6, 73.4, 72.1, 68.5,
C
(
3
7.4. HRMS (FAB): M + H calcd 583.2696, found 583.2704.
Tr iben zyl C-fu cose a ld eh yd e (6): yield 85%. 1H NMR (500
0
.25 mm) and visualized with UV light, p-anisaldehyde, and/or
ninhydrin staining. NMR spectra were obtained with a Bruker
ARX-500, ARX-400, or AM-360 spectrometer in CDCl or CD
OD. Spectra was referenced to residual CHCl and CH OH at
.26 and 3.3 ppm respectively. Unless otherwise noted spectra
were taken in CDCl . Coupling constants are listed in hertz.
MHz): δ 9.76 (t, 1H, J ) 1.4 Hz), 7.34-7.26 (m, 15H), 4.77 (d,
1
1
4
(
1
H, J ) 11.8 Hz), 4.75 (d, 1H, J ) 11.9 Hz), 4.68 (d, 1H, J )
2.0 Hz), 4.65 (d, 1H, J ) 11.8 Hz), 4.61 (d, 1H, J ) 11.8 Hz),
.53 (d, 1H, J ) 11.8 Hz), 3.95 (dt, 1H, J ) 10.9, 3.8 Hz), 3.86
3
3
-
3
3
7
m, 1H), 3.81 (m, 1H), 3.77-3.74 (m, 2H), 2.48 (dddd, 1H, J )
.7, 6.6, 6.6, 14.4 Hz), 2.43 (dddd, 1H, J ) 1.2, 6.8, 6.8, 14.4
Hz), 1.98 (m, 1H), 1.82 (m, 1H), 1.23(d, 3H, J ) 6.6 Hz).
Gen er a l P r oced u r e for Com p ou n d s in Ta ble 1 (see
compound data for equivalents used). Carboxylic acid in 1 M
MeOH, de-FMOCed Rink (1 equiv), isocyanide, and aldehyde in
3
IR spectra were obtained with a Nicolet 510P FT-IR spectrom-
eter. Optical rotations were obtained with a Perkin-Elmer
2
41MC polarimeter using a 1 dm pathlength at room temper-
ature (24 °C). Concentrations are reported in g/mL.
Rep r esen ta tive P r oced u r e for Deben zyla tion of Com -
p ou n d in En tr y 2. The C-glycoside (11 mg) was azeotroped
with toluene and dissolved in 100 µL of distilled MeOH. Pd-
1
M CH
evaporation to near dryness, the polymer was washed repeatedly
with CH Cl and MeOH. Treatment of the polymer with 15 mL
of 20% trifluroaceticacid in CH Cl and slow filtration followed
by vacuum evaporation provides the benzylated product. De-
benzylation with Pd(OH) on carbon with H gas gives the polyol.
2 2
Cl were combined. After 24 h of stirring and then
2
2
(
OH)
sphere. The solution was bubbled with H
then stirring was continued for 24 h under an atmosphere of H
2
on carbon (7 mg, Aldrich) was added under a N
2
atmo-
2
2
2
gas for 5 min and
2
2
2
gas. The solution was filtered through a small bed of Celite
followed by excessive rinsing with MeOH. The solvent was
evaporated, giving 9 mg of a clear yellow oil.
Rep r esen ta tive P r oced u r e for Cou p lin g F MOC Am in o
Acid s to Rin k Resin . The FMOC amino acid (4.6 mmol), DCC
F or a cetyla ted com p ou n d s: the polymer is rinsed after the
MCC reaction and then stirred with 4 mL of freshly prepared 1
M NaOMe for 2 h. After the solution is filtered and washed
with 5% HCl/MeOH and excess MeOH and CH
used to remove the compound from the resin.
2 2
Cl , TFA is then
(4.6 mmol), and HOBt (3.45 mmol) were combined in THF and
En tr y 1, R ) Bn : acid of C-galactose (2.0 equiv), aldehyde
of C-galactose (2.0 equiv), Rink polymer (1.0 equiv), MICA (5.0
equiv); 56% yield, crude was taken directly on. Deben zyl: yield
stirred for 20 min. The white DCU was filtered, transferring
the filtrate to 2.05 g of Rink (Advanced Chemtech, 0.56 mmol/
g). After 18 h of gentle stirring, the resin was washed with
9
1
(
9%, both diastereomers. IR (neat): ν max 3366, 2930, 1678,
alternating DMF, MeOH, and CH
2
Cl
2
.
-1
1
547, 1439, 1410, 1377, 1206, 1140, 1092, 1051 cm
.
H NMR
Gen er a l P r oced u r e for C-Glycosid e Ald eh yd e Oxid a -
tion . The aldehyde (1.0 equiv) was dissolved in tBuOH (20 mL
per 4.5 mmol of aldehyde), water (2 mL per 4.5 mmol of
500 MHz, D
2
O/CD OD 5/1): δ 4.53 (dd, 0.3H), 4.39 (dd, 0.7H,
3
J ) 8.2, 8.2 Hz), 3.86 (d, 0.7 H), 3.79-3.40 (m, 20H), 3.29-3.10
(
(
1
7
6
m, 5H), 2.75-2.60 (m, 2H), 2.42-2.21 (m, 2H), 2.15 (t, 1H), 1.71
aldehyde), and 2-methyl-2-butene (6.7 equiv). Na
2
H
2
PO
4
(1.3
13
m, 1H). C NMR (125.7 MHz, D
2
O/CD
3
OD 5/1): δ 175.3, 175.1,
equiv) and NaClO (1.3 equiv) were added to the solution and
2
74.5, 172.7, 129.7, 79.6, 79.6, 79.5, 78.0, 77.7, 77.5, 77.4, 77.2,
allowed to stir overnight. The tBuOH was then evaporated, and
the residue was redissolved in 25 mL of EtOAc and transferred
to a separatory funnel. Then 20 mL of saturated NH Cl was
4
5.0, 74.9, 74.8, 72.0, 71.6, 71.5, 71.4, 70.2, 70.2, 70.1, 62.5, 62.4,
2.3, 62.1, 53.6, 53.4, 52.7, 42.1, 39.4, 38.1, 34.4. HRMS (FAB):
M + H calcd 863.2933, found 863.2915.
En tr y 2: propionic acid (5.0 equiv), aldehyde of C-galactose
(2.0 equiv), Rink polymer (1.0 equiv), MICA (5.0 equiv); yield )
(
27) Forty-eight of the 96 wells were checked for successful formation
of product with positive ion electrospray mass spectroscopy, giving a
6% success rate with all failures attributed to the wells containing
1
54%, crude. H NMR (500 MHz): δ 7.59 (br, 1H), 7.39-7.26
8
(m, 20H), 7.12 (br, 1H), 4.97-4.31 (8H), 4.1-3.5 (sugar ring H,
the olefinic diacid. In addition, yields and purities were confirmed by
the isolation and characterization ( H NMR and mass spectra) of
compounds from eight larger scale reactions. (Bd6) 17.4 mg, 55.8%
yield; (Bh4) 14.0 mg, 47.4% yield; (Bd4) 11.0 mg, 38.0% yield; (Bf6)
.1 mg, 32.3% yield; (Bh1) 5.0 mg, 17.4% yield; (Bb1) 8.7 mg, 28.4%
7
8
2
H), 3.65 (s, 3H), 3.28 (d, 0.2 H, J ) 5.8 Hz), 3.16 (d, 0.8 H, J )
.7 Hz), 2.82 (bd, 1H, J ) 14.4 Hz), 2.40 (br, 2H), 2.27 (br, 1H),
.26 (br, 2H), 1.94 (br, 1H), 1.14 (t, 3H, J ) 7.1 Hz). Ma jor
1
9
d ia ster eom er : yield ) 20%, off prep TLC. IR (neat): ν max
3326, 2922, 2872, 1752, 1653, 1539, 1454, 1366, 1208, 1105 cm
-1
yield; (Bg5) 9.7 mg, 31.6% yield; (Bg4) 2.6 mg, 9.0% yield.
.

8
354 J . Org. Chem., Vol. 61, No. 23, 1996
Notes
1
crude. 1H NMR (360 MHz, CD
OD): δ 4.50 (m, 1H), 4.10 (m,
3
H NMR (400 MHz): δ 7.36-7.25(m, 20H), 6.27 (br, 1H), 4.95
d, 1H, J ) 11.9 Hz), 4.91 (d, 1H, J ) 11.0 Hz), 4.75 (d, 1H, J )
(
1
4
1H), 4.05-3.83 (bm, 4H), 3.74-3.61 (bm, 2H), 2.67-2.53 (bm,
4H), 2.17 (b, 1H), 2.02 (b, 1H); major diastereomer 3.65 (s, 3H),
1.21 (d, 3H, J ) 7.0 Hz), minor diastereomer 3.76 (s, 3H), 1.22
(s, 3H, J ) 7.0 Hz). HRMS (FAB) for acetylated methyl ester:
M + H calcd 547.2139, found 547.2126. IR (neat): ν max 2930,
1.8 Hz), 4.72 (d, 1H, J ) 11.9 Hz), 4.64 (d, 1H, J ) 10.9 Hz),
.61 (d, 1H, J ) 11.9 Hz), 4.47 (d, 1H, J ) 10.8 Hz), 4.32 (d, 1H,
J ) 10.9 Hz), 3.92 (dd, 1H, J ) 7.0, 17.6 Hz), 3.80 (d, 1H, J )
2
8
4
.6 Hz), 3.76-3.59 (m, 7H), 3.64 (s, 3H), 3.53 (brdd, 1H, J )
.0, 14.6 Hz), 3.18 (dd, 1H, J ) 2.1, 9.2 Hz), 2.95 (dd, 1H, J )
.3, 17.6 Hz), 2.19 (q, 2H, J ) 7.4 Hz), 2.05 (m, 2H), 1.13 (t, 3H,
-
1
1747, 1667, 1539, 1373, 1227, 1088, 1057 cm
.
En tr y 7: stearic acid (5.0 equiv), aldehyde of C-galactose (2.8
equiv), Rink polymer (1.0 equiv), MICA (5.0 equiv); yield )
1
3
J ) 7.4 Hz).
C NMR (100.6 MHz) (note: carbonyl carbons
absent due to very long T1’s): δ 138.4, 138.3, 138.3, 137.3, 128.6,
5.2%, 1H NMR (400 MHz, CD
3
OD): δ 4.67 (m, 1H, minor
6
1
1
4
28.5, 128.5, 128.4, 128.4, 128.3, 128.2, 127.9, 127.8, 127.7, 127.6,
27.6, 84.7, 79.9, 75.4, 75.2, 74.2, 74.0, 72.8, 71.3, 52.0, 50.0,
diastereomer) 4.57 (dd, 1H, J ) 6.2, 8.5 Hz, major diastereomer),
4
(
.06-3.34 (m, 10H), 2.34-2.13 (m, 2H), 1.98-1.79 (m, 2H), 1.58
0.3, 35.3, 29.6, 9.7. [R]
D
: +2.14 (c 0.015, CHCl
3
).
13
m, 2H), 1.27 (bm, 30H), 0.87 (m, 3H). C NMR (100.6 MHz,
En tr y 2, d eben zyl: yield ) 95%, crude. IR (neat): ν max
CD OD): two diastereomers, δ 176.4, 176.1, 175.0, 174.6, 172.8,
3
359, 2932, 1744, 1651, 1541, 1223, 1090 cm-1
.
1
H NMR (400
3
8
4
3
0.2, 78.1, 77.8, 76.2, 72.9, 72.4, 71.1, 70.9, 63.3, 63.0, 52.4, 52.0,
1.8, 37.0, 36.8, 30.7, 36.8, 35.4, 34.8, 33.0, 30.8, 30.7, 30.6, 30.5,
0.5, 30.4, 30.3, 24.2, 23.7, 14.4. HRMS (EI) for tetra-acetylated
MHz, CD
3
OD): δ 4.58 (dd, 1H, J ) 6.4, 9.3 Hz), 3.80 (m, 1H),
3
0
1
1
.71 (t, 3H), 3.62 (dd, 1H, J ) 3.6, 15.0 Hz), 3.55 (ddd, 1H, J )
.9, 3.5, 9.1 Hz), 3.42-3.34 (m, 3H), 2.32 (ddd, 1H, J ) 2.5, 9.4,
4.0 Hz), 2.24 (q, 2H, J ) 7.6 Hz), 1.83 (ddd, 1H, J ) 2.9, 6.5,
compound: M + H calcd 757.4487, found 757.4485. IR (neat):
ν max 3061, 2924, 2853, 1747, 1651, 1539, 1466, 1439, 1371,
1
3
4.0 Hz), 1.10 (t, 3H, J ) 7.6 Hz). C NMR (100.6 MHz, CD
3
-
-1
1
226, 1097, 1051, 910, 738, 704 cm
.
OD): δ 176.7, 174.8, 171.7, 80.4, 77.9, 76.3, 73.0, 71.1, 63.3, 52.6,
5
3
En tr y 8: p-toulualdehyde (5.0 equiv), fucose acid (3.0 equiv),
2.4, 41.9, 35.5, 29.8, 10.2. HRMS (FAB): M + H calcd
79.1717, found 379.1718. [R] : +18.4 (c 0.0076, CH OH).
En tr y 3: napthoic acid (5.0 equiv), aldehyde of C-fucose (2.0
Rink polymer (1.0 equiv), MICA (5.0 equiv); yield ) 24%, crude.
IR (neat): ν max 3291, 2926, 1636, 1539, 1516, 1455, 1377, 1204,
D
3
-
1
1
1
140, 1065, 689 cm
.
3 3
H NMR (500 MHz, 5:1 CDCl :CD OD):
equiv), Rink polymer (1.0 equiv), benzyl isocyanide (5.0 equiv);
yield ) 33%, crude. IR (neat): ν max 3285, 2928, 1636, 1533,
1
δ 7.19 (m, 6H), 7.06 (m, 4H), 5.33 (bm, 1H), 4.30 (bm, 3H), 3.83
(
(
3
bm, 1H), 3.76 (bm, 1H), 3.58 (m, +CD OH), 3.52 (bm, 1H), 2.53
455, 1356, 1244, 1101, 785, 733, 696 cm-1
.
1
H NMR (400
1
3
m, 2H), 2.26 (s, 3H), 1.12 (m, 3H). C NMR (100.6 MHz): two
MHz): δ 8.4-7.2 (m, 27H), 6.86 (t, 1H, J ) 5.9 Hz), 4.84 (d, 1H,
diastereomers, δ 1171.6, 170.5, 170.4, 137.9, 137.6, 134.3, 129.7,
J ) 11.7 Hz), 4.77 (d, 1H, J ) 12 Hz), 4.74 (d, 1H, J ) 11.7 Hz),
1
5
29.3, 128.3, 127.2, 127.2, 126.9, 77.2, 71.9, 70.7, 69.6, 68.0, 67.9,
6.7, 56.7, 43.2, 34.7, 33.1, 33.0, 29.5, 20.8, 15.8, 15.7. HRMS
4
.67 (d, 1H, J ) 11.7 Hz), 4.63 (d, 1H, J ) 11.7 Hz), 4.56 (d, 1H,
J ) 11.5 Hz), 4.38 (dd, 1H, J ) 5.4, 14.9 Hz), 4.24 (dt, 1H, J )
.7, 11.1 Hz), 4.14 (ddd, 1H, J ) 2.4, 6.4, 13.0 Hz), 4.03 (dd, 1H,
(FAB): M + H calcd 443.2182, found 443.2194.
4
En tr y 9: salicylic acid (6.1 equiv), aldehyde of C-galactose
3.8 equiv), Rink polymer (1.0 equiv), MICA (5.0 equiv); yield )
J ) 5.0, 8.0 Hz), 3.85 (dd, 1H, J ) 2.9, 8.1 Hz), 3.79 (t, 1H, J )
(
2
)
.7 Hz), 2.46 (ddd, 1H, J ) 6.0, 11.4, 14.4 Hz), 2.10 (ddd, 1H, J
1
3
53.1%, crude. IR (neat): ν max 3375, 2928, 1684, 1541, 1495,
4.0, 9.6, 14.0 Hz), 1.22 (t, 3H, 6.5 Hz).
C NMR (100.6
-
1
1
1
441, 1207, 1140, 845, 802, 758, 725 cm
.
H NMR (400 MHz,
MHz): δ 170.8, 169.3, 138.5, 138.3, 138.1, 137.8, 134.1, 133.7,
CD
3
OD): δ 7.86 (d, 1H, J ) 4.5 Hz), 7.37 (m, 1H), 6.90 (d, 2H,
1
1
6
7
33.4, 131.0, 130.1, 128.7-127 (m), 127.2, 126.4, 126.2, 126.0,
25.5, 125.4, 124.6, 124.5, 77.9, 77.2, 76.3, 76.1, 73.9, 73.4, 73.1,
9.1, 68.7, 51.4, 43.6, 30.3, 16.1. HRMS (FAB): M + H calcd
J ) 4.6 Hz), 4.11-3.21 (bm, 12H), 2.47 (bm, 1H), 2.03 (bm, 1H).
1
3
3
C NMR (100.6 MHz, CD OD): two diastereomers, δ 160.5,
1
5
34.9, 129.9, 120.3, 118.2, 117.4, 80.3, 78.1, 76.2, 73.0, 71.0, 63.1,
2.7, 35.8. HRMS (EI) for tetraacetylated compound: M + H
49.3591, found 749.3604. [R]
D
) -36.7 (c 0.0171, CHCl
3
).
En tr y 4: FMOC-alanine (4.0 equiv), aldehyde of C-fucose (1.0
calcd 610.2010, found 610.1994
equiv), Rink polymer (1.0 equiv), MICA (5.0 equiv); yield ) 17%,
crude. IR (neat): ν max 3293, 2924, 1739, 1691, 1645, 1537,
1
6
7
HRMS for select com p ou n d s fr om Ta ble 2: Bd6 (FAB)
M + H calcd 560.2584, found 560.2585; Bh4 (CI) M + H calcd
592.3234, found 592.3219; Bd4 (CI) M + H calcd 580.3234, found
580.3232; Bf6 (FAB) M + Na calcd 544.2271, found 544.2277;
Bh1 (FAB) M + H calcd 479.2393, found 479.2403; Bb1 (FAB)
M + H calcd 439.2080, found 439.2087; Bg5 (FAB) M + Na calcd
636.2897, found 636.2895; Bg4 (FAB) M + H calcd 602.3054,
found 602.3050.
453, 1260, 1090 cm-1
.
1
H NMR (400 MHz): δ 7.74 (d, 2H, J )
.1 Hz), 7.50 (t, 2H, J ) 8.4 Hz), 7.39 (t, 2H, J ) 7.4 Hz), 7.32-
.21 (m, 21H), 7.16 (br, 1H), 6.78 (br, 0.5H), 6.62 (br, 0.5H), 5.30
(
4
m, 1H), 4.71 (d, 1H, J ) 12.1 Hz), 4.67 (d, 1H, J ) 12.1 Hz),
.62 (d, 1H, J ) 12.0 Hz), 4.57 (d, 1H, J ) 12.4 Hz), 4.49 (d, 1H,
J ) 12.0 Hz), 4.68 (1H), 4.42 (dd, 2H, J ) 4.4, 11.5 Hz), 4.26
br, 1H), 4.15 (t, 1H, J ) 6.4 Hz), 4.05 (m, 2H), 3.87 (m, 1H),
(
3
.77 (m, 2H), 3.69 (s, 3H), 3.05 (br, 2H). HRMS (FAB): M + H
calcd 960.4435, found 960.4417.
Ack n ow led gm en t. Financial support from UCLA,
NIH Grant GM51095, and NSF-REU program Grant
CHE-9322079 are greatly appreciated.
En tr y 5: acid of C-fucose (3.0 equiv), aldehyde of C-galactose
(
3.0 equiv), Rink polymer (1.0 equiv), MICA (5.0 equiv); yield )
7
1
4
0
1
1.5%, crude. IR (neat): ν max 3345, 1682, 1539, 1435, 1206,
-
1 1
138 cm
.
3
H NMR (400 MHz, CD OD): δ 4.49 (dd, 0.3H, J )
, 11 Hz), 4.40 (dd, 0.7H, J ) 6, 6 Hz), 4.20 (m, 0.7H), 4.05 (m,
Su p p or tin g In for m a tion Ava ila ble: H NMR spectra for
1
.3H), 3.8-3.1 (m, 12H), 3.11 (s), 2.7-2.3 (m), 2.2 (m), 2.1 (m),
sugar components, compounds generated in Table 1, and select
compounds from Table 2 (25 pages). This material is contained
in libraries on microfiche, immediately follows this article in
the microfilm version of the journal, and can be ordered from
the ACS; see any current masthead page for ordering
information.
1
3
.85-1.55 (m), 1.0 (d, 3H, J ) 6.6 Hz). C NMR (100.6 MHz,
3
CD OD): two diastereomers δ 179.1, 174.5, 174.3, 173.6, 172.4,
1
7
7
21.7, 121.1, 121.1, 118.8, 115.9, 113.1, 83.6, 79.7, 79.6, 77.4,
7.3, 75.0, 74.7, 74.3, 72.5, 72.2, 72.0, 71.8, 71.7, 71.3, 70.9, 70.5,
0.2, 70.1, 69.0, 68.3, 62.5, 52.3, 42.0, 33.5, 33.3, 16.6, 15.7.
En tr y 6: succinic acid (5.0 equiv), aldehyde of C-fucose (2.5
equiv), Rink polymer (1.0 equiv), MICA (5.0 equiv); yield ) 56%,
J O960119J