J.-i. Kadokawa et al. / Carbohydrate Research 327 (2000) 341–344
343
1. Experimental
powder (9.18 g, 16.8 mmol, 42.5% yield); mp
158–160 °C; [h]D +59.7° (c 0.66, chloro-
1
form); H NMR (CDCl3): l 1.97–2.10 (4 s, 12
General.—TMSOTf, nitromethane, and liq-
uid alcohols as glycosyl acceptors were
purified by distillation under reduced pressure
prior to use. The other reagents were used
without further purification. NMR spectra
were recorded on a Varian Mercury 200 spec-
trometer. Melting points were determined on
a Yanako micro melting point apparatus. Op-
tical rotations were measured with a Jasco
DIP-370 digital polarimeter.
H, CH3CꢀO), 3.96–4.23 (m, 3 H, H-5, 6), 4.40
(m, 1 H, H-2), 5.21 (t, 1 H, J 9.2 Hz, H-4),
5.33 (t, 1 H, J 9.2 Hz, H-3), 5.60 (q, 1 H,
JHCCH 7.6, JHCOP 3.2 Hz, H-1), 6.41 (d, 1 H, J
8.8 Hz, NH), 7.58 (m, 10 H, C6H5). Anal.
Calcd for C26H30NO10P: C, 57.04; H, 5.52; N,
2.56. Found: C, 56.91; H, 5.50; N, 2.51.
General procedure for the glycosylation reac-
tions.—Under argon, 4 (0.100 g, 0.180 mmol)
and alcohol (0.360 mmol) were mixed in ni-
tromethane (2.00 mL) at rt. Then, Me3SiOTf
(0.180 mmol, 0.0353 mL) was added to the
solution and the mixture was heated under
reflux temperature for 2 h. The mixture was
diluted with CHCl3, washed with satd aq
NaHCO3, dried over Na2SO4, filtered, and
evaporated. The yields of respective isomers
were determined by the integrated ratio of the
anomeric peaks with an aromatic peak of
trimethyl hydroquinone as an internal stan-
2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-i-
-glucopyranosyl
D
diphenylphosphinate
(4)
[12].—Diphenyl N,N-diethylphosphoramidite
[21–23] (25.7 g, 99.8 mmol) in CH2Cl2 (100
mL) was added to a solution of 2-acetamido-
3,4,6-tri-O-acetyl-2-deoxy- -glucopyranose
D
[12] (13.7 g, 39.4 mmol) and 1,2,4-triazole
(10.9 g, 157 mmol) in CH2Cl2 (500 mL), and
stirred for 12 h at room temperature (rt). The
solution was evaporated, diluted with diethyl
ether, washed with ice-cold satd aq NaHCO3,
and water, dried over Na2SO4, filtered, and
dried in vacuo. Then the residue was dissolved
in CH2Cl2 (100 mL) and H2O2 (30 wt%, 50
mL) was added to the solution. After the
mixture was stirred for 1 h at rt, the solution
was washed with satd aq NaHCO3, dried over
Na2SO4, filtered, and dried in vacuo. The
crude product was purified by silica gel
column chromatography (1:3 hexane–
EtOAc), and the resulting material was
washed with diethyl ether to give 4 as a white
1
dard in the H NMR spectra of the reaction
mixtures (CDCl3). The obtained crude prod-
ucts were isolated by silica gel column chro-
matography. The analytical data of the
isolated a-glycosides are shown as follows.
Hexyl 2-acetamido-3,4,6-tri-O-acetyl-2-de-
oxy-h- -glucopyranoside.—[h]D +81.9° (c
D
1
1.5, chloroform); H NMR (CDCl3): l 0.88–
0.94 (t, 3 H, J 6.4 Hz, CH2CH3), 1.25–1.42
(m, 6 H, (CH2)3CH3), 1.58–1.71 (m, 2 H,
OCH2CH2), 1.96–2.10 (4 s, 12 H, CH3CꢀO),
3.56 (m, 2 H, OCH2CH2), 3.94 (m, 1 H, H-5),
4.17 (m, 2 H, H-6), 4.34 (m, 1 H, H-2), 4.83
(d, 1 H, J 3.8 Hz, H-1), 5.11 (t, 1 H, J 9.0 Hz,
H-4), 5.21 (t, 1 H, J 9.0 Hz, H-3), 5.67 (d, 1
H, J 9.6 Hz, NH). Anal. Calcd for
C20H33NO9: C, 55.67; H, 7.71; N, 3.25. Found:
C, 56.19; H, 8.23; N, 3.28.
Table 2
Glycosylation of 4 with various alcohols a
Entry
Glycosyl acceptor
Yield (%) b
a/b anomers
Cyclohexyl 2-acetamido-3,4,6-tri-O-acetyl-
1
2
3
4
5
1-Hexanol
Methanol
Cyclohexanol
Allyl alcohol
Cholesterol
57.8 (54.4)/trace
35.2/7.9
77.6 (63.6)/14.0
40.0 (22.3)/6.8
(28.0)/nd
2-deoxy-h- -glucopyranoside.—[h]D +89.8°
D
1
(c 0.76, chloroform); H NMR (CDCl3): l
0.83–1.86 (m, 10 H, ꢁ(CH2)5ꢁ), 2.09–1.95 (4 s,
12 H, CH3), 3.54 (m, 1 H, OCH(CH2)CH2),
4.00–4.21 (m, 3 H, H-5, 6), 4.31 (m, 1 H,
H-2), 4.98 (d, 1 H, J 3.8 Hz, H-1), 5.10 (t, 1
H, J 9.6 Hz, H-4), 5.22 (t, 1 H, J 9.6 Hz, H-3),
5.65 (d, 1 H, J 9.4 Hz, NH). Anal. Calcd for
C20H31NO9: C, 55.93; H, 7.28; N, 3.26. Found:
C, 55.90; H, 7.59; N, 3.31.
a Promoter; Me3SiOTf, solvent; nitromethane, temperature;
reflux, reaction time; 2 h, [4]:[glycosyl acceptor]:[Me3SiOTf]=
1.0:2.0:1.0.
b Determined by 1H NMR spectra using trimethylhy-
droquinone as an internal standard. Values in parentheses are
isolated yields by silica gel column chromatography.