584
H. Yamada, T. Hayashi / Carbohydrate Research 337 (2002) 581–585
(ca. 1 mmHg). A benzene solution of each glycosyl
donor (1.0 equiv) and an acceptor alcohol (1.1 equiv)
was evaporated to azeotropically remove traces of wa-
ter, and dissolved into the solvent (40 mL/mmol based
on the amount of a glycosyl donor) listed in Tables
1–4. The solution was added to a mixture of dried
tert-Butyl 2,3,4,6-tetra-O-benzyl-h-D-glucopyranside
(h-4)26. The product was purified by column chro-
matography on silica gel with 40:1 n-hexane–EtOAc to
give an anomeric mixture of 4. HPLC retention time:
26.12 min (flow rate: 1.95 mL/min, pressure: 189 kg/
cm2). The NMR spectral data were identical to the
literature data.
,
copper(II) triflate (1.1 equiv) and powdered 4 A molec-
ular sieves (0.6 g/mmol). The mixture was stirred under
the conditions listed in the tables. When the reaction
was completed, the mixture was filtered through a
cotton-Celite pad. Satd aq sodium hydrogen carbonate
was added to the filtrate, and it was extracted with
dichloromethane. The organic layer was washed with
brine, dried over anhyd magnesium sulfate, filtered, and
concentrated. Silica-gel column chromatography of the
crude product, eluting with a mixture of n-hexane and
EtOAc, gave an anomeric mixture of the glycosides.
The a/b ratios of the mixtures were detected by HPLC
tert-Butyl 2,3,4,6-tetra-O-benzyl-i-D-glucopyranside
(i-4)26. HPLC retention time: 32.83 min. The NMR
spectral data were identical to the literature data.
Methyl 2,3,4-tri-O-benzyl-6-O-(2,3,4,6-tetra-O-ben-
zyl-h/i-D-glucopyranosyl)-h-D .
-glucopyranoside (5)26,27
The product was purified by column chromatography
on silica gel with 4:1 n-hexane–EtOAc to give an
anomeric mixture of 5. The NMR spectral data were
identical to the literature data.
1
Acknowledgements
(compounds 2, 3, and 4) or by the H NMR spectrum
(5). Conditions of HPLC are provided in each table.
Products.—Cyclohexylmethyl 2,3,4,6-tetra-O-benzyl-
This work was partially supported by a Grant-in-Aid
for Scientific Research (Grant no. 13874078) from the
Japan Society for the Promotion of Science, The Naito
Foundation, and by a Sunbor Grant from Suntory
Institute for Bioorganic Research.
h-
-glucopyranside (a-2)24.—The product was purified
D
by column chromatography on silica gel with 4:1 n-hex-
ane–EtOAc to give an anomeric mixture of 2 that was
separated by HPLC. HPLC retention time: 7.48 min
(flow rate: 2.00 mL/min, pressure: 92 kg/cm2); 13C
NMR (100 MHz in CDCl3) l 25.8 (CH2), 25.9 (CH2),
26.6 (CH2), 30.0 (CH2), 30.3 (CH2), 37.7 (CH), 68.6
(CH2), 70.1 (CH), 73.1 (CH2), 73.5 (CH2), 74.0 (CH2),
75.2 (CH2), 75.7 (CH2), 77.9 (CH), 80.4 (CH), 82.2
(CH), 97.2 (CH), 127.7 (CH), 127.8 (CH), 127.8 (CH),
127.9 (CH), 128.0 (CH), 128.0 (CH), 128.1 (CH), 128.1
(CH), 128.5 (CH), 128.5 (CH), 128.5 (CH), 128.6 (CH),
138.2 (C), 138.5 (C), 138.6 (C), 139.1 (C). The 1H NMR
spectral data were identical to the literature data.24a
References
1. A partial list of C-1 substituents that have been activated
by TMSOTf are in Refs. 1–11. (a) For ꢀF: Hashimoto,
S.; Hayashi, M.; Noyori, R. Tetrahedron Lett. 1984, 25,
1379–1382;
(b) For ꢀOC(ꢁNH)CCl3: Schmidt, R. R. Angew. Chem.,
Int. Ed. Engl. 1986, 25, 212–235.
2. For ꢀOAc: Ogawa, T.; Beppu, K.; Nakabayashi, S. Car-
bohydr. Res. 1981, 93, C6–C9.
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Cyclohexylmethyl
2,3,4,6-tetra-O-benzyl-i-
D
-glu-
copyranside (i-2)24. HPLC retention time: 6.21 min;
13C NMR (100 MHz in CDCl3) l 25.7 (CH2), 25.7
(CH2), 26.4 (CH2), 29.7 (CH2), 30.0 (CH2), 38.0 (CH),
68.9 (CH2), 73.2 (CH2), 74.6 (CH2), 74.6 (CH), 74.7
(CH2), 75.4 (CH2), 75.5 (CH2), 77.8 (CH), 82.1 (CH),
84.5 (CH), 103.6 (CH), 127.3 (CH), 127.4 (CH), 127.4
(CH), 127.5 (CH), 127.6 (CH), 127.7 (CH), 127.8 (CH),
128.0 (CH), 128.1 (CH), 128.2 (CH), 138.1 (C), 138.2
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Kusumoto, S. Tetrahedron Lett. 1999, 40, 6591–6593.
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1
(C), 138.5 (C), 138.6 (C). The H NMR spectral data
were identical to the literature data.24a
8. For ꢀOP(OBn)2: Kondo, H.; Aoki, S.; Ichikawa, Y.;
Halcomb, R. L.; Ritzen, H.; Wong, C.-H. J. Org. Chem.
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T.; Abe, R.; Terashima, S. Bull. Chem. Soc. Jpn. 1986, 59,
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Cholesterol-3-yl 2,3,4,6-tetra-O-benzyl-h-D-glucopy-
ranside (h-3)25. The product was purified by column
chromatography on silica gel with 10:1 n-hexane–
EtOAc to give an anomeric mixture of 3 that was
separated by HPLC. HPLC retention time: 10.63 min
(flow rate: 2.50 mL/min, pressure: 166 kg/cm2). The
NMR spectral data were identical to the literature data.
Cholesterol-3-yl 2,3,4,6-tetra-O-benzyl-i-D-glucopy-
ranside (i-3)25. HPLC retention time: 13.02 min. The
NMR spectral data were identical to the literature data.