Restriction of Conformation in Galabiosides Via an O6-O2′-Methylene Bridge

Article abstract of DOI:10.1021/jo962371x

Treatment of 2-(trimethylsilyl)ethyl 2,3-di-O-acetyl-4-O-(3,4,6-tri-O-acetyl-α-D-galactopyranosyl)-β-D- galactopyranoside (12) and 2-(trimethylsilyl)ethyl 2,3-di-O-benzyl-β-D-glucopyranoside (15) with the novel reagent combination formaldehyde diphenylmer

Full text of DOI:10.1021/jo962371x

J . Org. Chem. 1997, 62, 3659-3665
3659
Restr iction of Con for m a tion in Ga la biosid es Via a n
O6-O2′-Meth ylen e Br id ge†
Michael Wilstermann, J oakim Balogh, and Go¨ran Magnusson*
Organic Chemistry 2, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124,
S-221 00 Lund, Sweden
Received December 18, 1996X
Treatment of 2-(trimethylsilyl)ethyl 2,3-di-O-acetyl-4-O-(3,4,6-tri-O-acetyl-R-D-galactopyranosyl)-
â-D-galactopyranoside (12) and 2-(trimethylsilyl)ethyl 2,3-di-O-benzyl-â-D-glucopyranoside (15) with
the novel reagent combination formaldehyde diphenylmercaptal-N-iodosuccinimide-trifluo-
romethanesulfonic acid [(PhS)2CH2/NIS/TfOH], gave the corresponding 6,2′-O- and 4,6-O-meth-
ylidene acetals 13 and 16 in 52% and 53% yield, respectively. Deacetylation of 13 gave
2-(trimethylsilyl)ethyl 4-O-R-D-galactopyranosyl-â-D-galactopyranoside (1). The conformation of 1
was similar to that of the non-acetalated parent glycoside.
In tr od u ction
Galabiose (GalR1-4Gal) is an integral part of a number
of biologically important glycolipids of the globo series.1
These glycolipids function inter alia as adhesion receptors
for bacterial surface (pilus) proteins and toxins, as
summarized in a recent publication from our laboratory.2
Our current research is directed toward the development
of efficient water soluble inhibitors of bacterial adhesion,
based on the structural motifs found in the naturally
occurring glycolipids.3
F igu r e 1.
Oligosaccharides and their analogs are subject to
enzymic hydrolysis. Therefore it can be anticipated that
of the saccharide-receptor complex by a favorable en-
their half-life in vivo is decreased, which reduces their
potential as bacterial adhesion inhibitors. Various meth-
ods to avoid enzymic hydrolysis have been suggested,
such as substitution of the intersaccharidic oxygen atom
by a sulfur atom (S-glycosides) or a methylene group (C-
glycosides). While this seems to work in some cases,4 the
inhibitory function can be severely impaired. For ex-
ample, a thiogalabioside of the above-mentioned type was
30 times less efficient than the parent compound in
inhibiting the binding of purified bacterial pilus protein
to covalently immobilized galabiose and globotriose.5
An alternative method for stabilizing the intersaccha-
ridic glycosidic bond might be by formation of a bridge
between the monosaccharide units. It is important that
the overall shape of the bioactive epitope of such a
molecule is conserved and that the bridge does not
interfere sterically with the binding site of the receptor.
The intersaccharidic bridge would in such cases introduce
a conformational bias and even contribute to the stability
tropic factor.
All galabiose-containing oligosaccharides studied so
far, including most of the synthetic analogs, have very
similar conformations,6 with the two galabiose-derived
hydroxyl groups HO-6 and HO-2′ situated close together.
The presence of an intramolecular hydrogen bond be-
tween these two hydroxyls was determined by NMR.5,6
It occurred to us that a methylene bridge might be an
acceptable substitute for the hydrogen bond and that the
bioactive conformation of galabiose would not be severely
altered. Furthermore, formaldehyde acetals are much
more stable than, for example, acetone acetals.7 How-
ever, as discussed below, the binding efficacy of the
bridged compound to bacterial receptor proteins was
reduced, despite reasonable conservation of the overall
conformation.
Methods for the creation of saccharide analogs with a
stable intersaccharidic bridge seem to be available only
for ganglioside lactams.8 We now report the formation
of a methylene bridge (Figure 1) between two closely
situated hydroxyl groups, using the novel reagent com-
bination (PhS)2CH2/NIS/TfOH.
† Dedicated to Professor Hans Paulsen on the occasion of his 75th
birthday.
X Abstract published in Advance ACS Abstracts, May 1, 1997.
(1) Kanfer, J . N., Hakomori, S.-I., Eds. 1983; Sphingolipid Biochem-
istry; Plenum: New York, 485 pp.
Syn th esis of Meth ylen e-Br id ged Ga la biosid es.
The synthesis of the bridged disaccharide 1 was envi-
sioned either via bridge-formation in a suitably semi-
protected galabioside, or by intramolecular glycoside
(2) Zhang, Z.; Magnusson, G. J . Org. Chem. 1995, 60, 7304-7315.
(3) (a) Kihlberg, J .; Magnusson, G. Pure & Appl. Chem. 1996, 68,
2119-2128. (b) Kihlberg, J .; Hultgren, S. J .; Normark, S.; Magnusson,
G. J . Am. Chem. Soc. 1989, 111, 6364-6368. (c) Striker, R.; Nilsson,
U.; Stoencipher, A.; Magnusson, G.; Hultgren, S. J . Mol. Microbiol.
1995, 16, 1021-1029. (d) Nilsson, U.; Striker, R. T.; Hultgren, S. J .;
Magnusson, G. Bioorg. Med. Chem. 1996, 4, 1809-1817. (e) Haataja,
S.; Tikkanen, K.; Nilsson, U.; Magnusson, G.; Karlsson, K.-A.; Finne,
J . J . Biol. Chem. 1994, 269, 27466-27472. (f) Nyholm, P. G.; Mag-
nusson, G.; Zhang, Z.; Norel, R.; Binnington-Boyd, B.; Lingwood, C.
A. Chem. Biol. 1996, 3, 263-275.
(6) (a) Bock, K.; Frejd, T.; Kihlberg, J .; Magnusson, G. Carbohydr.
Res. 1988, 176, 253-270. (b) Gro¨nberg. G.; Nilsson, U.; Bock, K.;
Magnusson, G. Carbohydr. Res. 1994, 257, 35-54.
(7) Tietze, L. F.; Seele, R.; Leiting, B.; Krach, T. Carbohydr. Res.
1988, 180, 253-262.
(8) (a) Ray, A. K.; Nilsson, U.; Magnusson, G. J . Am. Chem. Soc.
1992, 114, 2256-2257. (b) Wilstermann, M.; Kononov, L. O.; Nilsson,
U.; Ray, A. K.; Magnusson, G. J . Am. Chem. Soc. 1995, 117, 4742-
4754.
(4) Mehta, S.; Andrews, J . S.; J ohnston, B. D.; Svensson, B.; Pinto,
B. M. J . Am. Chem. Soc. 1995, 117, 9783-9790.
(5) Nilsson, U.; J ohansson, R.; Magnusson, G. Chem. Eur. J . 1996,
2, 295-302.
S0022-3263(96)02371-7 CCC: $14.00 © 1997 American Chemical Society

3660 J . Org. Chem., Vol. 62, No. 11, 1997
Wilstermann et al.
Sch em e 1
Sch em e 2
Legend: (a) NIS, molecular sieves 300 AW, Et2O, CH2Cl2, Ar,
-45 °C, TfOH. (b) H2, Pd/C, AcOH, 22 °C, 17 h. (c) (PhS)2CH2,
molecular sieves 300 AW, MeCN, CH2Cl2, Ar, -35 °C, NIS, TfOH,
3.8 h. (d) MeONa, MeOH.
Sch em e 3. Rea son a ble Rou te fr om Diols to
F or m a ld eh yd e Aceta ls, Usin g th e Rea gen t
Com bin a tion (P h S)2CH2/NIS/TfOH
Legend: (a) MeONa, MeOH. (b) (MeO)2CMe2, p-TsOH. (c) NaH,
BnBr, DMF, Ar, 22 °C, 3.5 h. (d) Aqueous AcOH, 90 °C, 90 min,
then Ac2O, pyridine, 15 h. (e) Ac2O, pyridine. (f) NaCNBH3,
molecular sieves 4 Å, THF, HCl‚Et2O, 22 °C.
formation of two methylene-linked galactose residues.
The former route was chosen because we already had
considerable experience of galabiose chemistry, and we
considered it to be a more general route, potentially
useful for other oligosaccharides. The 2-(trimethylsilyl)-
ethyl (TMSEt) group was chosen for anomeric protection,
due to its easy and high-yielding removal toward the end
of a synthesis.9
Synthesis of the building blocks needed for assembly
of 11 was performed via rather traditional, high-yielding
reactions, as shown in Scheme 1. Thus, the galactosyl
donor 7 was prepared from the known10 thioglycoside 3,
deacetylation of which (f4; 96%) and isopropylidenation9
of the product with 2,2-dimethoxypropane/PTSA gave 5
(81%) having only position 2 unprotected. Benzylation
of 5 (f6; 98%), followed by removal of the isopropylidene
groups and acetylation of the liberated hydroxyls, gave
the glycosyl donor 7 (93%). Acetylation of the known9
4,6-O-benzylidene acetal 8 (f9; 99%), followed by reduc-
tive opening11 of the benzylidene ring, gave the glycosyl
acceptor 10 (83%).
(96%), with HO-6 and HO-2′ exposed for methylidenation
(Scheme 2).
Standard acid-catalyzed activation of dimethoxy-
methane13 (or formaldehyde) in the presence of 12 failed
to produce the bridged saccharide 13; only a mixture of
the corresponding 6-O-methoxymethyl and 6,2′-O-bis-
(methoxymethyl) derivatives was obtained in low (∼20%)
yield. In contrast, activation of formaldehyde diphe-
nylmercaptal by N-iodosuccinimide and trifluoromethane-
sulfonic acid [(PhS)2CH2/NIS/TfOH], essentially as in the
glycosylation reaction described above, gave a reactive
species that converted 12 into the 9-membered ring
methylene-bridged galabioside 13 (52%). The novel
methylidenation reaction is supposed to proceed via the
intermediates depicted in Scheme 3. Removal of the
acetyl groups of 13 gave the bridged TMSEt-galabioside
1 (89%).
The glycosyl acceptor 10 was R-galactosylated with the
donor 7 under activation with N-iodosuccinimide/trifluo-
romethanesulfonic acid,12 giving the TMSEt-galabioside
11 (86%). No corresponding â-glycoside was isolated.
Hydrogenolysis of the two benzyl groups of 11 gave 12
(9) J ansson, K. Ahlfors, S.; Frejd, T.; Kihlberg, J .; Magnusson, G.;
Dahme´n, J .; Noori, G.; Stenvall, K. J . Org. Chem. 1988, 53, 5629-
5647.
(10) Yde, M.; De Bruyne, C. K. Carbohydr. Res. 1973, 26, 227-229.
(11) Garegg, P. J . Pure Appl. Chem. 1984, 56, 845-858.
(12) (a) Konradsson, P.; Mootoo, D. R.; McDewitt, R. E.; Fraser-Reid,
B. J . Chem. Soc., Chem. Commun. 1990, 270-272. (b) Veeneman, G.
H.; van Leeuwen, S. H.; van Boom, J . H. Tetrahedron Lett. 1990, 31,
1331-1334.
(13) Greene, T. W.; Wutz, G. M. Protective Groups in Organic
Synthesis; J ohn Wiley & Sons, Inc.: New York, 1991; pp 119-120.

Restriction of Conformation in Galabiosides
J . Org. Chem., Vol. 62, No. 11, 1997 3661
Sch em e 4
Sch em e 5
Legend: (a) Aqueous AcOH, 90 °C, 3 h. (b) (PhS)2CH2, molecular
sieves 300 AW, MeCN, CH2Cl2, Ar, -35 °C, NIS, TfOH, 3.8 h.
Legend: (a) CF3COOH, CH2Cl2, 22 °C, 30 min, and then
CCl3CN, DBU, 0 °C, 1 h. (b) HOCH2CH2Br, BF3‚Et2O, CH2Cl2, 0
°C, Ar, 50 min. (c) C18H37SH, Cs2CO3, DMF, Ar, 22 °C, 20 h. (d)
MeONa, MeOH, CH2Cl2, 22 °C, 90 min.
Possible ring-size limitations of the methylidenation
reaction were investigated using the diols 15 and 17
(Scheme 4). Compound 15 was obtained by hydrolysis
(in unexpectedly low yield; 42%) of the known9 4,6-O-
benzylidene acetal 14. Treatment of 15 under the meth-
ylidenation conditions described provided the 4,6-O-
methylidene acetal 16 (53%), whereas attempted
methylidenation of the vicinal diol 178b failed; only
degraded starting material was obtained after prolonged
reaction. The outcome of these two attempts can be
explained by the so-called Baldwin rules, stating that a
“6-endo-trig” mechanism is favored (cf. Scheme 3), whereas
a “5-endo-trig” mechanism is disfavored.14
It was rewarding to find that the 4,6-O-methylidene
acetal 16 could be formed, since methods are scarce for
conformational restriction of the hydroxymethyl group
of pyranosidic hexoses, which is often desired in receptor
studies with carbohydrates.15 The methylidenation reac-
tion described here introduces minimal steric bulk in the
molecule, and formyl acetals are generally more stable
against hydrolysis than other acetals.13
octadecanethiol and cesium carbonate in DMF19 gave the
glycolipid 20 (85%). Removal of the acetyl groups of 20
furnished the neoglycolipid 2 (86%).
Con for m a tion of Com p ou n d 1. Conformational
analysis of a large number of galabiose-containing dif
pentasaccharides and their derivatives (e.g., monodeoxy
analogs) by X-ray crystallography,20 NMR,6 and compu-
tational methods6 showed that they generally retain the
overall shape of the parent compound (e.g., B in Figure
2). In short, they all show a strong NOE effect between
H-4 and H-1′ of the galactose residues and, more impor-
tantly, a strong (∼0.5 ppm) downfield shift (compared to
1
methyl R-D-galactopyranoside; A in Figure 2) of the H-
NMR signal for H-5′, due to the close proximity of H-5′
and O-3 in galabiosides. The downfield shift is absent
in the 3-deoxy- and 3-C-methyl analogs of methyl
â-galabioside.6a
The conformations of 1 and its parent compound B
1
(Figure 2) were investigated by H-NMR and molecular
In addition to soluble glycosides (such as 1) for use as
inhibitors of proteins that bind to natural glycoconju-
gates,16 well-defined neoglycolipids17 are useful for coat-
ing of microtiter plates or for presentation on TLC plates.
The TMSEt galabioside 13 was transformed into the
neoglycolipid 2 (Scheme 5). Treatment of 13 with tri-
fluoroacetic acid in dichloromethane9 gave the corre-
sponding hemiacetal (quantitative yield), which was
converted without purification to the imidate18 18 (61%).
Glycosylation of 2-bromoethanol with 18 gave the 2-bro-
moethyl glycoside 19 (63%), treatment of which with
mechanics (MM3 force field)21 calculations. The 1H-NMR
signal was deshielded in both compounds, 0.2 ppm for 1
and 0.58 ppm for B. The difference in deshielding
indicates that the average H-5′-O-3 distance in 1 is
somewhat longer than in B. Compound 1 had strong
NOE contacts between one methylene-bridge hydrogen
and both H-1′ and H-2′, which is in agreement with the
calculated low-energy conformations (Figure 2).
Molecular mechanics calculations21 of 1, using reason-
able starting conformations for the nine-membered ring,
all converged to one of the two low-energy conformers
shown in Figure 2. The conformers of lowest energy had
a H-5′-O-3 distance of 2.7 and 3.1 Å and O2CH2-H-1′
and -H-2′ distances of 2.2-2.7 Å, respectively. These
(14) (a) Baldwin, J . E. J . Chem. Soc., Chem. Commun. 1976, 734-
736. (b) Baldwin, J . E.; Cutting, J .; Dupont, W.; Kruse, L.; Silbermann,
L.; Thomas, R. C. J . Chem. Soc., Chem. Commun. 1976, 736-738.
(15) (a) Lough, C.; Hindsgaul, O.; Lemieux, R. U. Carbohydr. Res.
1983, 120, 43-53. (b) Lemieux, R. U.; Wong, T. C.; Tho¨gersen, H. Can.
J . Chem. 1982, 60, 81-86. (c) Lindh, I.; Hindsgaul, O. J . Am. Chem.
Soc. 1991, 113, 216-223. (d) Bock, K.; Skrydstrup, T. J . Chem. Soc.,
Perkin Trans. 1, 1991, 1181-1186.
(16) Magnusson, G.; Chernyak, A. Ya.; Kihlberg, J .; Kononov, L. O.
In Neoglycoconjugates: Preparation and Application; Lee, Y. C., Lee,
R. T., Eds.; Academic Press: San Diego, CA, 1994; pp 53-143.
(17) Magnusson, G. Adv. Drug. Deliv. Rev. 1994, 13, 267-284.
(18) (a) Sinay¨, P. Pure Appl. Chem. 1978, 50, 1437-1452. (b)
Schmidt, R. R. Pure Appl. Chem. 1989, 61, 1257-1270.
(19) Dahme´n, J .; Frejd, T.; Magnusson, G.; Noori, G. Carbohydr.
Res. 1982, 111, c1-c4.
(20) Svensson, G.; Albertsson, J .; Svensson, C.; Magnusson, G.;
Dahme´n, J . Carbohydr. Res. 1986, 146, 29-38.
(21) (a) Allinger, N. L.; Yuh, Y. H.; Lii, J .-H. J . Am. Chem. Soc. 1989,
111, 8551-8566. (b) Allinger, N. L.; Rahman, M.; Lii, J .-H. J . Am.
Chem. Soc. 1990, 112, 8293-8307. (c) Molecular construction and
energy minimization were made with the MacMimic/MM3(92) package
from InStar Software, Ideon Research Park, S-223 70 Lund, Sweden.

3662 J . Org. Chem., Vol. 62, No. 11, 1997
Wilstermann et al.
F igu r e 2. (a) H-5′ chemical shifts, calculated H-5′-O-3 distances, and calculated interglycosidic torsional angles (Φ,Ψ). (b)
Stereorepresentation of the least-squares fit between low-energy conformations of compounds 1 and B; (top) lowest energy
conformation of 1; (bottom) next-lowest energy conformation of 1.
distances agree22 with the modest deshielding of H-5′ and
the strong NOE contacts between O2CH2 and H-1′/H-2′.
A comparison between the low-energy conformers of 1
and B was performed by a least-squares fit of the
coordinates for all pyranose ring atoms (Figure 2).21 The
two low-energy conformers of 1 gave, in comparison with
B, root mean square (RMS) values of 0.4 and 0.1 Å,
respectively.
Recogn ition of 1 by Ba cter ia l P r otein s. Three
bacterial proteins are known to use galabiose-containing
glycolipids as attachment points for the infectious pro-
cess: (i) the Escherichia coli pilus protein PapG in
complex with its chaperone PapD;23 (ii) Verotoxin24
produced by enterotoxic E. coli; and (iii) the Streptococcus
suis bacterium25 that carries a galabiose-recognizing
surface protein. A comparative binding study of the 6,2′-
O-methylidene galabiosides 1 and 2 and of the parent,
nonbridged, compound B was performed using the three
bacterial proteins.
Attempted inhibition by 1 of binding of the PapG/PapD
protein complex to a covalently anchored galabioside5
failed, as expected, since the PapG protein requires the
presence of intact HO-6 and HO-2′. Attempted binding
(23) Hultgren, S. J .; Lindberg, F.; Magnusson, G.; Kihlberg, J .;
Tennent, J .; Normark, S. Proc. Natl. Acad. Sci. U.S.A. 1989, 86, 4357-
4361.
(24) Lingwood, C. A. Adv. Lipid Res. 1993, 25, 189-212.
(25) Haataja, S.; Tikkanen, K.; Liukkonen, J .; Francois-Gerard, C.;
Finne, J . J . Biol. Chem. 1993, 268, 4311-4317.
(22) Tho¨gersen, H.; Lemieux, R. U.; Bock, K.; Meyer, B. Can. J .
Chem. 1982, 60, 44-57.

Restriction of Conformation in Galabiosides
J . Org. Chem., Vol. 62, No. 11, 1997 3663
of verotoxin3e,24 to the neoglycolipid 2 was also unsuc-
cessful for the same reason.
4-Meth ylp h en yl 1-th io-â-D-ga la ctop yr a n osid e (4). So-
dium methoxide (2 M, 3 mL) was added to a solution of 310
(12.5 g, 28.6 mmol) in dry MeOH (120 mL). The mixture was
stirred overnight and then neutralized with Duolite C-26 (H+)
Compound 1 showed a reduced (compared with B), but
still significant, inhibition of hemagglutination of S. suis
bacteria (S. Haataja, J . Finne, M. Wilstermann, and G.
Magnusson, unpublished results). S. suis uses HO-2, -3,
-4′, and -6′ for binding to galabiosides but not HO-6, -2′,
and -3′.3d Thus, the inhibitory efficiency of 1 is consistent
with a slightly altered conformation, which carries the
important hydroxyls somewhat differently positioned
than in the efficient inhibitor B. The calculated (MM3)
positional differences for HO-2, -3, -4′, and 6′, as mea-
sured in the least-squares-fitted low-energy conforma-
tions of 1 and B (Figure 2) were 0.7, 0.8, 0.2, and 1.0 Å
and 0.2, 0.3, 0.1, and 0.4 Å, respectively.
resin, filtered, and concentrated to give 4 (7.90 g, 96%); [R]22
D
1
-65 (c 1.0, MeOH); H NMR data (D2O), δ 7.44 (m, 2 H, Ar),
7.21 (m, 2 H, Ar), 4.64 (d, 1 H, J 9.5 Hz, H-1), 3.93 (d, 1 H, J
3.2 Hz, H-4), 3.75-3.51 (m, 5 H), 2.28 (s, 3 H, CH3); HRMS
calcd for C13H19O5S (M + H), 287.0953; found, 287.0940.
4-Meth ylp h en yl 3,4-O-Isop r op ylid en e-6-O-(2-m eth oxy-
isop r op yl)-1-th io-â-D-ga la ctop yr a n osid e (5). To a solution
of 4 (7.85 g, 27.4 mmol) in 2,2-dimethoxypropane (280 mL)
was added a catalytic amount of p-toluenesulfonic acid. The
mixture was stirred for 20 h and then neutralized with Et3N
and concentrated. The residue was chromatographed (SiO2,
heptane/EtOAc 2:1f1:1 + 0.2% Et3N) to give 5 (8.81 g, 81%);
1
[R]25 -10 (c 1.1, CHCl3); H NMR data (CDCl3), δ 7.46 (m, 2
D
H, Ar), 7.12 (m, 2 H, Ar), 4.39 (d, 1 H, J 10.2 Hz, H-1), 4.19
(dd, 1 H, J 5.4, 2.1 Hz, H-4), 4.07 (dd, 1 H, J 6.9, 5.5 Hz, H-3),
3.86 (ddd, 1 H, J 7.1, 5.5, 2.2 Hz, H-5), 3.74 (dd, 1 H, J 9.8,
6.7 Hz, H-6), 3.67 (dd, 1 H, J 9.8, 5.5 Hz, H-6), 3.54 (dd, 1 H,
J 10.2, 6.9 Hz, H-2), 3.23 (s, 3 H, OMe), 2.33 (s, 3 H, PhCH3),
1.41, 1.38, 1.37, 1.33 (s, 3 H each, CCH3); HRMS calcd for
C20H30O8S (M), 398.1763; found, 398.1771.
We reported earlier that exchange of the intersaccha-
ridic oxygen atom in compound B for a sulfur atom
caused a 30-fold drop in inhibitory efficiency (PapG/PapD
binding).5 In the present investigation, introduction of
the methylene bridge caused a similar decrease in
inhibitor efficency of 1, although the conformational
change in the galabiose moiety was rather limited. This
gives reason for contemplating the structural preciseness
needed in the design of analogs of natural ligands.
4-Meth ylp h en yl 2-O-Ben zyl-3,4-O-isop r op ylid en e-6-O-
(2-m eth oxyisop r op yl)-1-th io-â-D-ga la ctop yr a n osid e (6).
To a solution of 5 (8.71 g, 21.9 mmol) in dry DMF (70 mL)
under Ar was added sodium hydride (1.76 g, 44 mmol, 60% in
mineral oil). The mixture was stirred for 1 h and then cooled
to 0 °C, and benzyl bromide (5.2 mL, 44 mmol) was added
dropwise. The mixture was left at room temperature for 3.5
h, and excess sodium hydride was destroyed by addition of
MeOH (5 mL). The mixture was partitioned between ether
and water, the aqueous phase was extracted with ether, and
the combined organic phases were dried (Na2SO4), filtered, and
concentrated. The residue was chromatographed (SiO2, hep-
Exp er im en ta l Section
Melting points are uncorrected. NMR spectra were recorded
at 500, 400, or 300 MHz. 1H-NMR spectral assignments were
made by the double-resonance techniques COSY, HETCOR,
and TOCSY. Concentrations were made using rotary evapora-
tion with bath temperature at or below 40 °C. TLC was
performed on Kieselgel 60 F254 plates (Merck). Column
chromatography was performed using SiO2 (Matrex LC-gel:
60A, 35-70 MY, Grace). Compounds 3,10 8,9 14,9 and 178b were
prepared essentially as described.
tane/EtOAc 3:1 + 0.2% Et3N) to give 6 (10.5 g, 98%); [R]25
D
1
-13 (c 1.0, CHCl3); H NMR data (CDCl3), δ 7.48-7.07 (m, 9
H, Ar), 4.81 (d, 1 H, J 11.4 Hz, CH2Ph), 4.68 (d, 1 H, J 11.4
Hz, CH2Ph), 4.58 (d, 1 H, J 9.7 Hz, H-1), 4.22 (m, 2 H), 3.82
(ddd, 1 H, J 7.0, 5.3, 1.9 Hz, H-5), 3.74 (dd, 1 H, J 9.8, 6.7 Hz,
H-6), 3.67 (dd, 1 H, J 9.8, 5.5 Hz, H-6), 3.50 (dd, 1 H, J 9.7,
2.2 Hz, H-2), 3.19 (s, 3 H, OMe), 2.32 (s, 3 H, PhCH3), 1.40,
1.36, 1.35, 1.34 (s, 3 H each, CCH3); HRMS calcd for C27H36O6S
(M), 488.2233; found, 488.2244.
2-(Tr im eth ylsilyl)eth yl 6,2′-O-Meth ylid en e-4-O-r-D-ga -
la ctop yr a n osyl-â-D-ga la ctop yr a n osid e (1). Sodium meth-
oxide (1.1 M, 0.050 mL) was added to a solution of 13 (61 mg,
0.092 mmol) in dry MeOH (2.5 mL), and the mixture was
stirred for 90 min and then neutralized with Duolite C-26 (H+)
resin, filtered, and concentrated. The residue was chromato-
graphed (SiO2, CH2Cl2/MeOH 6:1 + 0.1% Et3N) to give 1 (37
4-Meth ylp h en yl 3,4,6-Tr i-O-a cetyl-2-O-ben zyl-1-th io-â-
D-ga la ctop yr a n osid e (7). Compound 6 (10.3 g, 21.1 mmol)
was dissolved in aqueous acetic acid (120 mL, 80%), and the
mixture was kept at 90 °C for 90 min and then concentrated
and co-concentrated with toluene. The residue was acetylated
with acetic anhydride-pyridine (80 mL, 1:1) overnight. The
mixture was concentrated and co-concentrated with toluene.
The residue was chromatographed (SiO2, heptane/EtOAc 2:1)
to give 7 (9.9 g, 93%). An analytical sample was crystallized
mg, 89%); [R]22 +23 (c 0.5, H2O); 1H NMR data (D2O), δ 5.12
D
(d, 1 H, J 4.5 Hz, H-1′), 4.79 (d, 1 H, J 7.5 Hz, OCH2O), 4.75
(d, 1 H, J 7.5 Hz, OCH2O), 4.28 (d, 1 H, J 7.9 Hz, H-1), 4.00-
3.74 (m, 9 H), 3.63-3.58 (m, 3 H), 3.55 (dd, 1 H, J 10.1, 4.0
Hz, H-3), 3.33 (dd, 1 H, J 10.1, 7.9 Hz, H-2), 0.90 (m, 2 H,
CH2Si), -0.10 (s, 9 H, SiMe3); 13C NMR data (D2O), δ 103.9,
102.4, 94.6, 84.0, 78.1, 73.2, 72.7, 72.1, 69.7, 69.2, 69.1, 64.0,
61.8, 18.4, -1.7; HRMS calcd for C18H34O11SiNa (M + Na),
477.1768; found, 477.1775.
from heptane; mp 139-140 °C; [R]25 +8 (c 1.0, CHCl3); 1H
D
NMR data (CDCl3), δ 7.50-7.12 (m, 9 H, Ar), 5.40 (d, 1 H, J
3.3 Hz, H-4), 5.01 (dd, 1 H, J 9.6, 3.3 Hz, H-3), 4.86 (d, 1 H, J
11.0 Hz, CH2Ph), 4.67 (d, 1 H, J 9.7 Hz, H-1), 4.58 (d, 1 H, J
11.0 Hz, CH2Ph), 4.18 (dd, 1 H, J 11.2, 7.0 Hz, H-6), 4.10 (dd,
1 H, J 11.2, 6.3 Hz, H-6), 3.87 (t, 1 H, J 6.7 Hz, H-5), 3.72 (t,
1 H, J 9.7 Hz, H-2), 2.35 (s, 3 H, PhCH3), 2.13, 2.04, 1.93 (s, 3
H each, OAc); 13C NMR data (CDCl3), δ 170.4, 170.1, 169.9,
138.1, 137.9, 132.8, 129.7, 129.3, 128.4, 127.9, 88.2, 75.5, 75.3,
74.2, 74.1, 67.7, 61.7, 21.2, 20.71, 20.70; HRMS calcd for
C26H30O8SNa (M + Na), 525.1559; found, 525.1569.
2-(Octa d ecylth io)eth yl 6,2′-O-Meth ylid en e-4-O-r-D-ga -
la ctop yr a n osyl-â-D-ga la ctop yr a n osid e (2). Sodium meth-
oxide (1.1 M, 0.013 mL) was added to a solution of 20 (23 mg,
0.026 mmol) in dry MeOH (1 mL) and dry CH2Cl2 (0.2 mL).
After 90 min, aqueous acetic acid (0.040 mL, 0.87 M) was
added, immediately followed by Et3N (0.25 mL), and the
mixture was concentrated. The residue was chromatographed
(SiO2, CH2Cl2/MeOH 8:1+0.1% Et3N) to give 2 (15 mg, 86%);
[R]23D +8 (c 1.0, CHCl3/MeOH 1:1); 1H NMR data (CDCl3/CD3-
OD 2:1), δ 5.09 (d, 1 H, J 4.4 Hz, H-1′), 4.82 (d, 1 H, J 7.2 Hz,
OCH2O), 4.75 (d, 1 H, J 7.2 Hz, OCH2O), 4.18 (d, 1 H, J 7.5
Hz, H-1), 4.04 (t, 1 H, J 8.7 Hz), 3.96-3.60 (m, 11 H), 3.50
(dd, 1 H, J 10.0, 3.9 Hz, H-3), 3.42 (dd, 1 H, J 10.0, 7.4 Hz,
H-2), 2.72 (t, 2 H, J 7.0 Hz, CH2S), 2.51 (t, 2 H, J 7.4 Hz, SCH2),
1.55 (m, 2 H), 1.37-1.16 (m, 30 H), 0.84 (t, 3 H, J 6.9 Hz, CH3);
13C NMR data (CDCl3), δ 104.3, 103.2, 93.9, 84.1, 78.4, 73.0,
72.5, 72.0, 71.9, 69.7, 69.3, 62.7, 62.3, 32.6, 32.2, 31.6, 30.0-
29.2, 23.0, 14.2; HRMS calcd for C33H62O11SNa (M + Na),
689.3911; found, 689.3914.
2-(Tr im et h ylsilyl)et h yl 2,3-Di-O-a cet yl-4,6-O-b en zyl-
id en e-â-D-ga la ctop yr a n osid e (9). Compound 89 (307 mg,
0.83 mmol) was acetylated with acetic anhydride/pyridine (20
mL, 1:1) overnight. The mixture was concentrated and co-
concentrated with toluene, and the residue was chromato-
graphed (SiO2, heptane/EtOAc 1:1 + 0.1% Et3N) to give 9 (371
1
mg, 99%); [R]25 +46 (c 1.1, CHCl3); H NMR data (CDCl3), δ
D
7.55-7.35 (m, 5 H, Ar), 5.52 (s, 1 H, CHPh), 5.39 (dd, 1 H, J
10.4, 8.0 Hz, H-2), 4.97 (dd, 1 H, J 10.4, 4.7 Hz, H-3), 4.53 (d,
1 H, J 8.0 Hz, H-1), 4.40-4.32 (m, 2 H), 4.10-4.00 (m, 2 H),
3.61-3.51 (m, 2 H), 2.08, 2.06, (s, 3 H each, OAc), 0.97 (m, 2

3664 J . Org. Chem., Vol. 62, No. 11, 1997
Wilstermann et al.
H, CH2Si), 0.01 (s, 9 H, SiMe3); 13C NMR data (CDCl3), δ 170.9,
169.3, 137.5, 129.1, 128.2, 126.4, 101.1, 100.5, 73.5, 72.2, 69.0,
68.7, 66.8, 66.3, 20.9, 17.9, -1.4; HRMS calcd for C22H34O8-
SiNa (M + Na), 477.1920; found, 477.1915.
2-(Tr im et h ylsilyl)et h yl 2,3-Di-O-a cet yl-6,2′-O-m et h -
ylid en e-4-O-(3,4,6-tr i-O-a cetyl-r-D-ga la ctop yr a n osyl)-â-D-
ga la ctop yr a n osid e (13). A mixture of 12 (50 mg, 0.077
mmol), formaldehyde diphenylmercaptal (21 mg, 0.092 mmol),
molecular sieves (100 mg, AW 300), dry MeCN (1.7 mL), and
dry CH2Cl2 (0.66 mL) was stirred at room temperature for 1 h
under Ar, then cooled to -35 °C. To the cooled mixture was
added dropwise a solution of N-iodosuccinimide (86 mg, 0.383
mmol) and trifluoromethanesulfonic acid (0.002 mL, 0.023
mmol) in dry MeCN (0.4 mL). After 3 h 50 min, Et3N (0.05
mL) was added and the mixture was filtered (Celite), diluted
with CH2Cl2, and successively washed with saturated aqueous
Na2S2O3, saturated aqueous NaHCO3, and water, dried (Na2-
SO4), filtered, and concentrated. The residue was chromato-
graphed (SiO2, heptane/EtOAc 1:1 + 0.1% Et3N) to give 13
(26 mg, 52%); [R]22D +71 (c 1.0, CHCl3); 1H NMR data (CDCl3),
δ 5.52 (dd, 1 H, J 3.4, 1.1 Hz, H-4′), 5.32 (dd, 1 H, J 10.4, 3.4
Hz, H-3′), 5.18 (dd, 1 H, J 10.8, 7.6 Hz, H-2), 5.12 (d, 1 H, J
4.2 Hz, H-1′), 4.85 (dd, 1 H, J 10.8, 3.7 Hz, H-3), 4.78 (d, 1 H,
J 7.2 Hz, OCH2O), 4.72 (d, 1 H, J 7.2 Hz, OCH2O), 4.43 (m, 1
H, H-5′), 4.41 (d, 1 H, J 7.6 Hz, H-1), 4.21-4.09 (m, 3 H), 4.00-
3.91 (m, 4 H), 3.85 (dd, 1 H, J 9.5, 7.5 Hz, H-5), 3.50 (dt, 1 H,
J 9.8, 6.6 Hz, OCH2), 2.12, 2.10, 2.07, 2.05, 2.03 (s, 3 H each,
OAc), 0.95 (m, 2 H, CH2Si), 0.01 (s, 9 H, SiMe3); 13C NMR data
(CDCl3), δ 170.8, 170.5, 170.1, 169.9, 169.3, 103.9, 100.3, 93.0,
81.1, 74.9, 72.3, 69.2, 68.8, 67.9, 67.1, 66.7, 62.0, 60.8, 21.1,
2-(Tr im eth ylsilyl)eth yl 2,3-Di-O-a cetyl-6-O-ben zyl-â-D-
ga la ctop yr a n osid e (10). Compound 9 (6.94 g, 15.3 mmol),
NaCNBH3 (9.6 g, 153 mmol), and molecular sieves (7 g, 4 Å)
were suspended in dry THF (160 mL). Saturated etheral HCl
was added dropwise until the gas evolution ceased and TLC
showed that 9 had been consumed. Solid NaHCO3, CH2Cl2
(300 mL), and saturated aqueous NaHCO3 (50 mL) were
added, the mixture was filtered (Celite), and the phases were
separated. The aqueous phase was extracted with CH2Cl2, and
the combined organic phases were dried (Na2SO4), filtered, and
concentrated. The residue was chromatographed (SiO2, toluene/
EtOAc 5:1 f 3:1) to give 10 (5.78 g, 83%); [R]25 -9 (c 1.0,
D
CHCl3); 1H NMR data (CDCl3), δ 7.35-7.29 (m, 5 H, Ar), 5.25
(dd, 1 H, J 10.3, 7.9 Hz, H-2), 4.93 (dd, 1 H, J 10.3, 3.2 Hz,
H-3), 4.60 (d, 1 H, J 11.1 Hz, CH2Ph), 4.55 (d, 1 H, J 11.1 Hz,
CH2Ph), 4.46 (d, 1 H, J 7.9 Hz, H-1), 4.14 (brt, 1 H, J 3.7 Hz,
H-5), 4.00 (m, 1 H), 3.82-3.67 (m, 3 H), 3.55 (dt, 1 H, J 9.9,
6.6 Hz, OCH2), 2.09, 2.04, (s, 3 H each, OAc), 0.93 (m, 2 H,
CH2Si), 0.00 (s, 9 H, SiMe3); 13C NMR data (CDCl3), δ 170.3,
169.5, 137.6, 128.5, 127.9, 127.8, 100.7, 73.8, 73.6, 73.1, 69.5,
69.1, 68.1, 67.2, 20.93, 20.87, 18.0, -1.4; HRMS calcd for
C
22H32O8SiNa (M + Na), 475.1764; found, 475.1773.
20.9, 20.8, 20.7, 20.6, 17.9, -1.4; HRMS calcd for C28H44O16
-
2-(Tr im eth ylsilyl)eth yl 2,3-Di-O-a cetyl-6-O-ben zyl-4-O-
SiNa (M + Na), 687.2296; found, 687.2282.
(3,4,6-tr i-O-a cetyl-2-O-ben zyl-r-D-ga la ctop yr a n osyl)-â-D-
ga la ctop yr a n osid e (11). A mixture of 7 (1.44 g, 2.86 mmol),
10 (1.00 g, 2.20 mmol), molecular sieves (800 mg, AW 300),
N-iodosuccinimide (742 mg, 3.30 mmol), dry Et2O (60 mL), and
dry CH2Cl2 (20 mL) was stirred at room temperature for 1 h
under Ar and then cooled to -45 °C. Trifluoromethanesulfonic
acid (0.029 mL, 0.33 mmol) was added to the cooled mixture.
After 2.5 h, Et3N (1 mL) was added, the mixture was filtered
(Celite), diluted with CH2Cl2 and successively washed with
saturated aqueous Na2S2O3, saturated aqueous NaHCO3, and
water, dried (Na2SO4), filtered, and concentrated. The residue
was chromatographed (SiO2, toluene/EtOAc 4:1f1:1) to give
2-(Tr im eth ylsilyl)eth yl 2,3-Di-O-ben zyl-â-D-glu cop yr a -
n osid e (15). Compound 149 (224 mg, 0.408 mmol) was
dissolved in aqueous acetic acid (80%, 7.5 mL), and the mixture
was kept at 90 °C for 3 h and then concentrated and
co-concentrated with toluene. The residue was chromatho-
graphed (SiO2, heptane/EtOAc 1:1) to give 15 (79 mg, 42%);
[R]22 -21 (c 1, CHCl3); 1H NMR data (CDCl3), δ 7.45-7.24
D
(m, 10 H, Ar), 4.99 (d, 1 H, J 11.0 Hz, CH2Ph), 4.97 (d, 1 H, J
11.6 Hz, CH2Ph), 4.74 (d, 1 H, J 11.1 Hz, CH2Ph), 4.69 (d, 1
H, J 11.5 Hz, CH2Ph), 4.48 (d, 1 H, J 7.4 Hz, H-1), 4.02 (m, 1
H, OCH2), 3.93-3.74 (m, 2 H, H-6), 3.64 (m, 1 H, OCH2), 3.56
(m, 1 H, H-4), 3.46 (t, 1 H, J 8.8 Hz, H-3), 3.44 (brt, 1 H, J 8.2
Hz, H-2), 3.35 (m, 1 H, H-5), 2.44 (d, 1 H, J 2.4 Hz, OH), 2.14
(t, 1 H, J 3.5 Hz, OH), 1.05 (m, 1 H, CH2Si), 0.04 (s, 9 H,
SiMe3); 13C NMR data (CDCl3), δ 138.9, 138.8, 129.1, 128.9,
128.5, 128.4, 128.2, 103.8, 84.3, 82.4, 75.6, 75.2, 75.1, 70.8, 68.3,
63.1, 19.1, -1.0; HRMS calcd for C25H36O6SiNa (M + Na),
483.2179; found, 483.2165.
11 (1.56 g, 86%); [R]25 +42 (c 0.9, CHCl3); 1H NMR data
D
(CDCl3), δ 7.32-7.22 (m, 10 H, Ar), 5.52 (dd, 1 H, J 3.4, 1.3
Hz, H-4′), 5.41 (dd, 1 H, J 10.6, 3.3 Hz, H-3′), 5.18 (dd, 1 H, J
10.6, 7.8 Hz, H-2), 4.89 (d, 1 H, J 4.0 Hz, H-1′), 4.86 (dd, 1 H,
J 10.6, 2.9 Hz, H-3), 4.65 (d, 1 H, J 12.0 Hz, CH2Ph), 4.57 (m,
2 H), 4.46 (d, 1 H, J 7.8 Hz, H-1), 4.32 (d, 1 H, J 11.8 Hz,
CH2Ph), 4.25 (d, 1 H, J 11.8 Hz, CH2Ph), 4.18-4.12 (m, 2 H),
4.07 (dd, 1 H, J 10.8, 5.8 Hz, H-6′), 4.00 (m, 1 H), 3.86 (dd, 1
H, J 9.7, 6.0 Hz, H-6) 3.85 (dd, 1 H, J 10.5, 3.5 Hz, H-2′), 3.72
(t, 1 H, J 6.1 Hz, H-5′), 3.63 (dd, 1 H, J 9.8, 6.1 Hz, H-6), 3.54
(dt, 1 H, J 9.8, 6.8 Hz, OCH2), 2.11, 2.05, 2.03, 1.98 (s, 3 H
each, OAc), 0.97 (m, 2 H, CH2Si), 0.02 (s, 9 H, SiMe3); 13C NMR
data (CDCl3), δ 171.1, 171.0, 170.5, 170.2, 169.5, 138.6, 138.5,
128.84, 128.77, 128.2, 128.1, 128.03, 128.00, 101.0, 100.8, 74.9,
74.2, 73.9, 73.7, 73.5, 70.2, 69.8, 68.9, 68.8, 67.5, 67.3, 61.2,
21.4, 21.24, 21.23, 21.13, 21.12, 18.4, -1.0; HRMS calcd for
C41H56O16SiNa (M + Na), 855.3235; found, 855.3226.
2-(Tr im eth ylsilyl)eth yl 2,3-Di-O-a cetyl-4-O-(3,4,6-tr i-O-
a cetyl-r-D-ga la ctop yr a n osyl)-â-D-ga la ctop yr a n osid e (12).
Compound 11 (1.50 g, 1.82 mmol) was hydrogenated (H2, Pd/
C, 10%, 500 mg, 1 atm) in acetic acid (40 mL) overnight. The
mixture was filtered (Celite) and concentrated. The residue
was chromatographed (SiO2, heptane/EtOAc 1:2) to give 12
(1.14 g, 96%); [R]25D +84 (c 1.0, CHCl3); 1H NMR data (CDCl3),
δ 5.48 (dd, 1 H, J 3.3, 1.2 Hz, H-4′), 5.20 (m, 2 H), 4.94 (d, 1
H, J 3.1 Hz, H-1′), 4.84 (dd, 1 H, J 10.7, 2.9 Hz, H-3), 4.52 (d,
1 H, J 7.8 Hz, H-1), 4.51 (m, 1 H, H-5′), 4.30 (dd, 1 H, J 3.0,
1.0 Hz, H-4), 4.17 (dd, 1 H, J 10.9, 7.8 Hz, H-6′), 4.08 (dd, 1 H,
J 10.8, 6.0 Hz, H-6′), 4.03-3.94 (m, 4 H), 3.85 (m, 1 H), 3.68
(m, 1 H, H-5), 3.55 (dt, 1 H, J 9.9, 6.2 Hz, OCH2), 3.08 (brs, 1
H), 2.12, 2.08, 2.06, 2.05, 2.04 (s, 3 H each, OAc), 0.96 (m, 2
H, CH2Si), 0.02 (s, 9 H, SiMe3); 13C NMR data (CDCl3), δ 171.2,
171.03, 171.02, 170.6, 169.5, 102.5, 101.2, 78.4, 73.43, 73.42,
70.8, 69.4, 68.6, 68.2, 68.0, 61.4, 61.2, 21.32, 21.28, 21.2, 21.11,
21.09, 18.4, -1.0; HRMS calcd for C27H44O16SiNa (M + Na),
675.2296; found, 675.2293.
2-(Tr im et h ylsilyl)et h yl 2,3-Di-O-b en zyl-4,6-O-m et h -
ylid en e-â-D-glu cop yr a n osid e (16). Compound 15 (40 mg,
0.087 mmol) was treated as descibed in the preparation of 13.
Column chromathography (SiO2, heptane/EtOAc 8:1) gave 16
(22 mg, 53%); [R]22 +4 (c 1.0, CHCl3); 1H NMR data (CDCl3),
D
δ 7.39-7.25 (m, 10 H, Ar), 5.10 (d, 1 H, J 6.2 Hz, OCH2O),
4.92 (d, 1 H, J 11.0 Hz, CH2Ph), 4.89 (d, 1 H, J 11.4 Hz, CH2-
Ph), 4.80 (d, 1 H, J 11.4 Hz, CH2Ph), 4.76 (d, 1 H, J 11.0 Hz,
CH2Ph), 4.64 (d, 1 H, J 6.3 Hz, OCH2O), 4.49 (d, 1 H, J 7.7
Hz, H-1), 4.23 (dd, 1 H, J 10.4, 4.8 Hz, H-6), 3.98 (m, 1 H,
OCH2), 3.68 (t, 1 H, J 9.0 Hz, H-3), 3.63 (m, 1 H, OCH2), 3.51
(t, 1 H, J 10.2 Hz, H-6), 3.45-3.38 (m, 2 H, H-2,4), 3.32 (dt, 1
H, J 9.7, 4.5 Hz, H-5), 1.04 (dd, 2 H, J 9.3, 7.9 Hz, CH2Si),
0.04 (s, 9 H, SiMe3); 13C NMR data (CDCl3), δ 142.7, 138.5,
138.4, 129.1, 128.34, 128.30, 128.1, 127.9, 127.7, 127.6, 103.6,
93.6, 82.3, 81.4, 80.9, 75.3, 75.0, 68.6, 68.0, 66.2, 18.6, -1.4;
HRMS calcd for C26H36O6SiNa (M + Na), 495.2179; found,
495.2180.
2,3-Di-O-a cetyl-6,2′-O-m eth ylid en e-4-O-(3,4,6-tr i-O-a c-
etyl-r-D-ga la ctop yr a n osyl)-r-D-ga la ctop yr a n osyl Tr ich lo-
r oa cetim id a te (18). Compound 13 (100 mg, 0.150 mmol) was
dissolved in CH2Cl2 (0.75 mL), trifluoroacetic acid (1.5 mL)
was added,9 and the mixture was stirred for 30 min. n-Propyl
acetate (5 mL) and toluene (10 mL) were added, and the
mixture was concentrated. The residue was dissolved in a
mixture of dry CH2Cl2 (3 mL) and trichloroacetonitrile (0.485
mL, 4.8 mmol) at 0 °C under Ar. Diazabicycloundecane (DBU,
0.033 mL, 0.22 mmol) was added, and after 1 h the mixture
was concentrated. The residue was chromatographed (SiO2,
heptane/EtOAc 1:1 + 0.1% Et3N) to give 18 (65 mg, 61%); [R]22
D

Restriction of Conformation in Galabiosides
J . Org. Chem., Vol. 62, No. 11, 1997 3665
+128 (c 1.0, CHCl3); 1H NMR data (CDCl3), δ 8.62 (s, 1 H,
NH), 6.63 (d, 1 H, J 3.4 Hz, H-1), 5.52 (dd, 1 H, J 3.7, 1.1 Hz,
H-4′), 5.40 (dd, 1 H, J 11.2, 3.4 Hz, H-2), 5.33 (dd, 1 H, J 10.4,
3.4 Hz, H-3′), 5.28 (dd, 1 H, J 11.2, 3.5 Hz, H-3), 5.15 (d, 1 H,
J 4.2 Hz, H-1′), 4.77 (d, 1 H, J 7.2 Hz, OCH2O), 4.72 (d, 1 H,
J 7.2 Hz, OCH2O), 4.42 (m, 2 H), 4.36 (dd, 1 H, J 3.4, 1.8 Hz,
H-4), 4.16 (dd, 1 H, J 10.8, 9.0 Hz), 4.08-4.02 (m, 2 H), 3.99
(dd, 1 H, J 10.4, 4.1 Hz, H-2′), 3.82 (dd, 1 H, J 9.8, 7.4 Hz,
H-3′), 2.12, 2.10, 2.07, 2.05, 2.03 (s, 3 H each, OAc); 13C NMR
data (CDCl3), δ 171.1, 170.8, 170.53, 170.51, 170.4, 161.4,
104.4, 94.3, 93.4, 81.6, 75.3, 71.0, 69.2, 69.1, 68.1, 67.5, 67.2,
Ar. After 20 h, the mixture was diluted with ether, washed
with water, dried (Na2SO4), filtered, and concentrated. Col-
umn chromatography (SiO2, heptane/EtOAc 1:1 + 0.1% Et3N)
gave 20 (33.4 mg, 85%); [R]22 +56 (c 1.0, CHCl3); 1H NMR
D
data (CDCl3), δ 5.51 (brd, 1 H, J 2.5 Hz, H-4′), 5.32 (dd, 1 H,
J 10.3, 3.4 Hz, H-3′), 5.20 (dd, 1 H, J 10.8, 7.7 Hz, H-2), 5.12
(d, 1 H, J 4.1 Hz, H-1′), 4.85 (dd, 1 H, J 10.7, 3.7 Hz, H-3),
4.78 (d, 1 H, J 7.2 Hz, OCH2O), 4.73 (d, 1 H, J 7.2 Hz, OCH2O),
4.46 (d, 1 H, J 7.7 Hz, H-1), 4.42 (m, 1 H, H-5′), 4.21-4.14 (m,
2 H), 4.10 (t, 1 H, J 8.9 Hz), 4.01-3.93 (m, 4 H), 3.85 (dd, 1 H,
J 9.3, 7,2 Hz), 3.62 (dt, 1 H, J 10.1, 7.5 Hz, OCH2), 2.70 (m, 2
H, CH2S), 2.53 (t, 2 H, J 7.4 Hz, SCH2), 2.12, 2.11, 2.09, 2.05,
2.04 (s, 3 H each, OAc), 0.89 (t, 3 H, J 6.8 Hz, CH3); 13C NMR
data (CDCl3), δ 171.1, 170.9, 170.5, 170.4, 169.8, 104.3, 101.2,
93.4, 81.4, 75.3, 72.9, 72.5, 69.5, 69.3, 69.2, 68.2, 67.1, 62.4,
61.2, 33.0, 32.3, 31.8, 30.2-29.3, 23.1, 21.5, 21.3, 21.2, 21.12,
21.06, 14.6; HRMS calcd for C43H72O16SNa (M + Na), 899.4439;
found, 899.4425.
62.2, 61.1, 21.7, 21.3, 21.13, 21.07; HRMS calcd for C25H32O16
-
NCl3Na (M + Na), 730.0684; found, 730.0675.
2-Br om oeth yl 2,3-Di-O-a cetyl-6,2′-O-m eth ylid en e-4-O-
(3,4,6-t r i-O-a cet yl-r-D-ga la ct op yr a n osyl)-â-D-ga la ct op y-
r a n osid e (19). Boron trifluoride etherate (0.0027 mL, 0.021
mmol) was added to a mixture of 18 (50 mg, 0.070 mmol),
2-bromoethanol (0.0075 mL, 0.106 mmol), and dry CH2Cl2 (1
mL) at 0 °C under Ar. After 50 min, the mixture was diluted
with CH2Cl2, washed with saturated aqueous NaHCO3, dried
(Na2SO4), filtered, and concentrated. Column chromatography
(SiO2, heptane/EtOAc 1:1 + 0.1% Et3N) gave 19 (30 mg, 63%);
Ack n ow led gm en t. We are grateful to Dr. Scott
Hultgren, Washington University, St. Louis, MO, for a
generous gift of purified PapG/PapD protein; Dr. Clifford
Lingwood, Hospital for Sick Children, Toronto, Canada,
for the binding studies with verotoxin; and Dr. J ukka
Finne, University of Turku, Finland, for the inhibition
studies with S. suis bacteria. This work was supported
by the Swedish Research Council for Engineering Sci-
ences and the Swedish Natural Science Research Coun-
cil.
[R]25 +79 (c 1.0, CHCl3); 1H NMR data (CDCl3), δ 5.51 (dd, 1
D
H, J 3.4, 1.1 Hz, H-4′), 5.32 (dd, 1 H, J 10.4, 3.4 Hz, H-3′),
5.22 (dd, 1 H, J 10.8, 7.7 Hz, H-2), 5.13 (d, 1 H, J 4.2 Hz, H-1′),
4.86 (dd, 1 H, J 10.8, 3.7 Hz, H-3), 4.78 (d, 1 H, J 7.2 Hz,
OCH2O), 4.73 (d, 1 H, J 7.2 Hz, OCH2O), 4.49 (d, 1 H, J 7.7
Hz, H-1), 4.42 (m, 1 H), 4.21-4.05 (m, 4 H), 4.01-3.93 (m, 3
H), 3.86 (dd, 1 H, J 9.4, 7,2 Hz), 3.79 (dt, 1 H, J 11.0, 6.9 Hz,
OCH2), 3.48 (dd, 2 H, J 6.8, 5.6 Hz, CH2Br), 2.12, 2.11, 2.10,
2.05, 2.04 (s, 3 H each, OAc); 13C NMR data (CDCl3), δ 171.1,
170.9, 170.5, 170.4, 169.9, 104.3, 101.3, 93.4, 81.2, 75.3, 73.0,
72.4, 69.5, 69.1, 68.2, 67.2, 62.4, 61.2, 30.6, 21.5, 21.34, 21.26,
21.13, 21.07; HRMS calcd for C25H35O16BrNa (M + Na),
693.1006; found, 693.0993.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra
and 1H NMR data with peak assignments for all title com-
pounds described in the experimental section (16 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.
2-(Oct a d ecylt h io)et h yl 2,3-Di-O-a cet yl-6,2′-O-m et h -
ylid en e-4-O-(3,4,6-tr i-O-a cetyl-r-D-ga la ctop yr a n osyl)-â-D-
ga la ctop yr a n osid e (20). Compound 19 (30 mg, 0.045 mmol),
octadecanethiol (25.6 mg, 0.090 mmol), and cesium carbonate
(17.5 mg, 0.054 mmol) were dissolved in dry DMF (2 mL) under
J O962371X