J. Zhang et al. / Carbohydrate Research 342 (2007) 797–805
803
5.27 (dd, 1H, J 9.3, 9.2 Hz,) 4.70–4.65 (m, 2H,
CH2@CH–CH2O), 4.03 (dd, 1H, J 5.4, 10.8 Hz, H-6a),
3.94–3.77 (m, 3H, H-2, H-4, H-6), 3.59–3.51 (m, 1H,
H-5), 3.08 (br s, 1H, OH), 1.50, 1.37 (2s, 6H, Me2C).
Anal. Calcd for C20H24O9: C, 58.82; H, 5.92. Found:
C, 59.03; H, 5.77.
4.55 (m, 2H, CH2@CH–CH2O), 4.01–3.75 (m, 4H, H-
3, H-4, H-6), 3.51-3.43 (m, 1H, H-5), 1.50, 1.43 (2s,
6H, Me2C). Anal. Calcd for C22H26Cl3NO8: C, 49.04;
H, 4.86; N, 2.60. Found: C, 49.31; H, 5.02; N, 2.98.
2.4.2. 3-O-Benzyl-1-O-ethyloxycarbonyl-4,6-O-isopropyl-
idene-2-O-trichloroacetimidoyl-b-D-glucopyranose (21).
22
1
2.3.8. 3-O-Benzoyl-1-O-ethyloxycarbonyl-4,6-O-isoprop-
ylidene-a,b-D-glucopyranose (18). Yield 3.21 g (81%),
Yield 2.45 g (93%), syrup. ½aꢁD +27 (c 0.5, CHCl3); H
NMR (CDCl3, 300 MHz): d 8.65 (s, 1H, CNHCCl3),
7.32–7.24 (m, 5H, Ar-H), 5.72 (d, 1H, J 8.0, H-1), 5.41
(dd, 1H, J 8.0, 8.1 Hz, H-2), 4.83–4.71 (m, 2H, CH2Ph),
4.21 (q, 2H, J 7.1 Hz, OCH2CH3), 4.01–3.75 (m, 4H, H-
3, H-4, H-6), 3.51–3.45 (m, 1H, H-5), 1.49, 1.43 (2s, 6H,
Me2C), 1.26 (t, 3H, J 7.1 Hz, OCH2CH3). Anal. Calcd
for C21H26Cl3NO8: C, 47.88; H, 4.97; N, 2.66. Found:
C, 47.75; H, 4.71; N, 2.29.
22
foamy solid. For b isomer: ½aꢁD +33 (c 1.0, CHCl3);
1H NMR (CDCl3, 300 MHz): d 8.08–7.44 (m, 5H, Bz-
H), 5.58 (d, 1H, J 8.0 Hz, H-1), 5.26 (dd, 1H, J 9.2,
9.3 Hz, H-3), 4.30–4.23 (m, 2H, CH3CH2O), 4.04 (dd,
1H, J 5.0, 10.5 Hz, H-6a), 3.92–3.76 (m, 3H, H-2, H-4,
H-6b), 3.59–3.50 (m, 1H, H-5), 3.00 (d, 1H, J 4.3 Hz,
OH), 1.49, 1.37 (2s, 6H, Me2C), 1.33 (t, 3H, J 9.4 Hz,
CH3CH2O). Anal. Calcd for C19H24O9: C, 57.57; H,
6.10. Found: C, 57.84; H, 6.02.
2.4.3. 2-O-Acetyl-3-O-allyl-4,6-O-isopropylidene-a,b-D-
glucopyranosyl trichloroacetimidate (24). Yield 1.87 g
22
2.3.9. 1-O-Acetyl-3-O-benzoyl-4,6-O-isopropylidene-a,b-
D-glucopyranose (19). Yield 2.64 g (72%), foamy solid.
(84%), syrup. ½aꢁD +20 (c 0.5, CHCl3); 1H NMR
(CDCl3, 300 MHz): d 8.66 (s, 1H, CNHCCl3, b-ano-
mer), 8.60 (s, 1H, CNHCCl3, a-anomer), 6.45 (d, 1H,
J 3.9 Hz, H-1, a-anomer), 5.83 (d, 1H, J 8.2 Hz, H-1,
b-anomer), 5.93–5.76 (m, 1H, CH2@CH–CH2O, a,b-
anomer), 5.29–5.12 (m, 2H, CH2@CH–CH2O, a,b-ano-
mer), 5.21 (dd, 1H, J 8.1, 8.2 Hz, H-2, b-anomer), 4.99
(dd, 1H, J 3.9, 8.2 Hz, H-2, a-anomer), 4.31–3.43 (m,
5H, H-3, H-4, H-5, H-6), 2.05 (s, 3H, CH3CO, a-ano-
mer), 2.04 (s, 3H, CH3CO, b-anomer), 1.52, 1.43 (2s,
6H, Me2C, a-anomer), 1.51, 1.42 (2s, 6H, Me2C, b-ano-
mer). Anal. Calcd for C16H22Cl3NO7: C, 43.02; H, 4. 96;
N, 3.14. Found: C, 42.83; H, 4.70; N, 3.30.
22
½aꢁD +36 (c 1.1, CHCl3); 1H NMR (CDCl3, 300 MHz): d
8.09–7.43 (m, 5H, Bz-H, a,b-anomer), 6.21 (d, 0.11H, J
4.0 Hz, H-1, a-anomer), 5.73 (d, 0.88H, J 8.1 Hz, H-1,
b-anomer), 5.40 (dd, 0.11H, J 9.2, 9.3 Hz, H-3, a-ano-
mer), 5.26 (dd, 0.88H, J 9.2, 9.3 Hz, H-3, b-anomer),
4.36–3.50 (m, 5H, H-2–6, a,b-anomer), 2.97 (br s, 1H,
OH), 2.20 (s, 0.33H, CH3CO, a-anomer), 215 (s,
2.64H, CH3CO, b-anomer), 1.49, 1.37 (2s, 6H, Me2C,
a,b-anomer). Anal. Calcd for C18H22O8: C, 59.01; H,
6.05. Found: C, 59.29; H, 6.23.
2.4. General procedure for the preparation of compounds
20, 21, 24, and 25
2.4.4. 2-O-Acetyl-3-O-benzyl-4,6-O-isopropylidene-a,b-
D-glucopyranosyl
trichloroacetimidate
(25). Yield
22
1
Compound 14, or 15, or 13, or 16 (5 mmol) and K2CO3
(2.0 g) were dried under high vacuum for 4 h and then
CH2Cl2 (20 mL) was added to the mixture. Then under
N2 atmosphere, CCl3CN (1.0 mL, 10 mmol) was added,
the mixture was stirred for 2 h, at the end of which time
DBU (135 lL, 0.9 mmol) was added. The reaction mix-
ture was stirred for 12 h, and TLC (2:1 petroleum ether–
EtOAc) indicated that the reaction was complete. After
filtration, the mixture was concentrated under dimin-
ished pressure to give a residue, purification of the crude
product on a silica gel column with 5:1 petroleum ether–
EtOAc as the eluent furnished the desired compounds.
1.96 g (79%), syrup. ½aꢁD +12 (c 0.5, CHCl3); H NMR
(CDCl3, 300 MHz): d 8.65 (s, 1H, CNHCCl3, b-ano-
mer), 8.58 (s, 1H, CNHCCl3, a-anomer), 7.35–7.24 (m,
5H, Ar-H, a,b-anomer), 6.46 (d, 1H, J 3.8 Hz, H-1, a-
anomer), 5.83 (d, 1H, J 7.9 Hz, H-1, b-anomer), 5.24
(dd, 1H, J 7.8, 7.9 Hz, H-2, b-anomer), 5.00 (dd, 1H,
J 3.8, 7.9 Hz, H-2, a-anomer), 4.88–4.64 (m, 2H,
CH2Ph, a,b-anomer), 4.02–3.46 (m, 5H, H-3, H-4, H-
5, H-6), 1.97 (s, 3H, CH3CO, a-anomer), 1.96 (s, 3H,
CH3CO, b-anomer), 1.51, 1.45 (2s, 6H, Me2C, a-ano-
mer), 1.50, 1.44 (2s, 6H, Me2C, b-anomer). Anal. Calcd
for C20H24Cl3NO7: C, 48.36; H, 4.87; N, 2.82. Found: C,
48.00; H, 4.59; N, 3.05.
2.4.1. 3-O-Benzyl-1-O-allyloxycarbonyl-4,6-O-isopropyl-
idene-2-O-trichloroacetimidoyl-b-D-glucopyranose (20).
2.5. General procedure for the coupling reaction: synthesis
of compounds 27, 29, and 31
22
1
Yield 2.39 g (89%), syrup. ½aꢁD +19 (c 0.5, CHCl3); H
NMR (CDCl3, 300 MHz): d 8.65 (s, 1H, CNHCCl3),
7.31–7.23 (m, 5H, Ar-H), 5.94–5.68 (m, 1H,
CH2@CH–CH2O), 5.71 (d, 1H, J 8.0 Hz, H-1), 5.41
(dd, 1H, J 8.0 8.1 Hz, H-2), 5.38–5.23 (m, 2H,
CH2@CH–CH2O), 4.83–4.71 (m, 2H, CH2Ph), 4.67–
Compound 12 (120 mg, 0.30 mmol) and sugar trichloro-
acetimidates 26, or 28, or 30 (0.36 mmol) were dried
together under high vacuum for 4 h, then dissolved in
anhyd CH2Cl2 (10 mL). TMSOTf (1.8 lL, 0.010 mmol)