2710
W. Li et al. / Carbohydrate Research 342 (2007) 2705–2715
was added tert-butylchlorodiphenylsilane (0.16 mL,
0.61 mmol) in anhyd CH2Cl2 (1 mL) dropwise under
N2. After stirring at rt for 4 h, the mixture was concen-
trated. The residue was subjected to silica gel column
chromatography (15:1 petroleum ether–EtOAc), afford-
MS: calcd for C87H94O21Na (M+Na+), 1497.6180.
Found: 1497.6164.
3.9. Diosgenyl 3,6-anhydro-2,4-di-O-a-L-rhamnopyran-
osyl-b-D-glucopyranoside (30)
23
ing 27 (147 mg, 45%) as a white solid: ½aꢃD ꢁ157.5 (c
1
0.69, CHCl3); H NMR (300 MHz, CDCl3): d 7.76 (d,
To a solution of 29 (80 mg, 0.054 mmol) in MeOH
(2 mL) and CH2Cl2 (2 mL) was added NaOMe portion-
wise until the pH of the solution was between 10–11.
After stirring for 1 h at room temperature, the reaction
mixture was neutralized, filtered, and then concentrated.
The residue was purified by silica gel column chroma-
tography (5:1 CH2Cl2–MeOH) to afford 30 (20 mg,
J = 6.6 Hz, 2H, Ar–H), 7.68 (d, J = 6.0 Hz, 2H,
Ar–H), 7.48–7.40 (m, 6H, Ar–H), 5.38 (br s, 1H, H-6),
5.11 (s, 1H, H-10), 4.50–4.38 (m, 2H), 4.30 (d,
J = 9.6 Hz, 1H), 4.23–4.20 (m, 1H), 4.15 (br s, 1H),
3.83–3.79 (m, 1H), 3.73 (br s, 1H), 3.67–3.47 (m, 3H),
3.42–3.35 (m, 1H), 2.48–2.43 (m, 1H), 2.27–2.19 (m,
1H), 1.10 (s, 9H, TBDPS-(CH3)3), 1.02 (s, 3H, H-19),
0.97 (d, J = 6.9 Hz, 3H, H-21), 0.80 (m, 6H, H-18,
H-27); 13C NMR (75 MHz, CDCl3): d 140.7, 135.8
(2C), 135.5 (2C), 132.0, 131.6, 130.5, 130.4, 128.1 (2C),
128.0 (2C), 121.5, 109.3, 101.3, 80.8, 76.6, 73.4, 73.1,
72.6, 71.5, 70.6, 66.9, 62.2, 56.5, 50.2, 41.6, 40.3, 39.8,
38.3, 37.4, 37.0, 32.1, 31.9, 31.5, 31.4, 30.3, 29.5, 28.8,
26.8 (3C), 20.9, 19.4, 19.1, 17.1, 16.3, 14.5; MALDITOF
MS: calcd for C49H68O7SiNa (M+Na+), 819.4626.
Found: 819.4637.
23
1
43%) as a white solid: ½aꢃD ꢁ95.6 (c 0.74, MeOH); H
NMR (400 MHz, pyridine-d5): d 5.70–5.64 (m, 3H,
H-10, Rha–H-1), 5.36 (br s, 1H, H-6), 4.80–4.33 (m,
13H), 4.05 (dd, J = 3.0, 10.0 Hz, 1H), 3.95–3.85 (m,
1H), 3.68–3.59 (m, 2H), 2.82–2.77 (m, 1H), 2.54–2.51
(m, 1H), 1.75 (d, J = 6.1 Hz, 3H, Rha–CH3), 1.71 (d,
J = 6.1 Hz, 3H, Rha–CH3), 1.23 (d, J = 6.9 Hz, 3H,
H-21), 1.07 (s, 3H, H-19), 0.92 (s, 3H, H-18), 0.78 (d,
J = 5.6 Hz, 3H, H-27); 13C NMR (100 MHz, pyridine-
d5): d 141.0, 121.8, 109.4, 101.5, 101.1, 98.1, 81.2 (2C),
77.4, 74.1, 73.9, 73.8, 73.2, 72.7 (2C), 72.5 (2C), 72.3,
71.5, 70.5, 70.2, 67.0, 63.1, 56.8, 50.5, 42.1, 40.6, 40.0,
39.1, 37.7, 37.3, 32.4, 32.3, 32.0, 31.8, 30.7, 30.4, 29.4,
21.3, 19.5, 18.7, 18.6, 17.4, 16.5, 15.1; MALDITOF
MS: calcd for C45H70O15Na (M+Na+), 873.5. Found:
873.4.
3.8. Diosgenyl 3,6-anhydro-2,4-di-O-(2,3,4-tri-O-benzoyl-
a-L-rhamnopyranosyl)-b-D-glucopyranoside (29)
To a mixture of 2,3,4-tri-O-benzoyl-L-rhamnopyranosyl
trichloroacetimidate 19 (372 mg, 0.60 mmol), diol 26
˚
(112 mg, 0.20 mmol) and 4 A MS in anhyd CH2Cl2
3.10. Diosgenyl 3,6-anhydro-2-O-(tert-butyldiphenyl-
silyl)-4-O-(2,3,4-tri-O-benzoyl-a-L-rhamnopyranosyl)-
b-D-glucopyranoside (31)
(5 mL) at 0 ꢁC under N2 was added TMSOTf (3.5 lL,
0.020 mmol). The mixture was allowed to warm up to
room temperature and was stirred for another 0.5 h.
Et3N was added to quench the reaction. The resulting
mixture was filtered and concentrated. The residue was
applied to silica gel column chromatography (15:1
petroleum ether–EtOAc, 25:1 toluene–EtOAc) to pro-
To a mixture of compound 27 (116 mg, 0.14 mmol), imi-
˚
date 19 (178 mg, 1.4 mmol), and 4 A MS in anhyd
CH2Cl2 (5 mL) at 0 ꢁC under N2 was added TMSOTf
(2.4 lL, 0.014 mmol). After stirring for 0.5 h, the mix-
ture was allowed to warm up to room temperature
and was stirred for another 4 h. The reaction was then
quenched with Et3N. The resulting mixture was then
filtered and concentrated. The residue was applied to
silica gel column chromatography (30:1 petroleum
ether–EtOAc) to provide 31 (113 mg, 65%) as a white
23
vide 29 (97 mg, 33%) as a white solid: ½aꢃD +58.7 (c
1.36, CHCl3); 1H NMR (400 MHz, CDCl3): d 8.15–
8.10 (m, 4H, Ar–H), 7.94–7.88 (m, 4H, Ar–H), 7.62–
6.82 (m, 22H, Ar–H), 6.04 (br s, 1H, Rha–H-1), 5.92–
5.75 (m, 5H), 5.51–5.47 (m, 2H), 5.32 (s, 1H, H-6),
5.28 (s, 1H, H-10), 4.61–4.52 (m, 3H), 4.45–4.38 (m,
3H), 4.29 (d, J = 9.9Hz, 1H), 4.04 (br s, 1H), 3.99–
3.79 (m, 1H), 3.85–3.74 (m, 1H), 3.49–3.45 (m, 1H),
3.37 (t, J = 10.9 Hz, 1H), 2.79–2.70 (m, 1H), 2.35–2.25
(m, 1H), 1.48 (d, J = 6.2 Hz, 3H, Rha–CH3), 1.43 (d,
J = 6.2 Hz, 3H, Rha–CH3), 0.97 (m, 6H, H-19, H-21),
0.78 (m, 6H, H-18, H-27); 13C NMR (100 MHz,
CDCl3): d 166.1, 165.9, 165.8, 165.7, 165.3, 164.7,
140.6, 133.4–127.6 (36C), 121.7, 109.3, 97.0, 96.9, 96.4,
80.8, 80.5, 73.5, 72.4, 72.3, 71.7, 71.4, 71.3 (2C), 70.8,
70.6, 70.5, 68.0, 67.0, 66.9, 41.6, 40.3, 39.8, 38.4, 37.3,
37.0, 32.1, 31.9, 31.5, 31.4, 30.3, 29.8, 29.7 (3C), 28.8,
20.8, 19.3, 17.8, 17.7, 17.1, 16.2, 14.5, 14.1; MALDITOF
23
1
solid: ½aꢃD +7.3 (c 1.37, CHCl3); H NMR (300 MHz,
CDCl3): d 8.14 (d, J = 7.5 Hz, 2H, Ar–H), 7.92 (d,
J = 7.5 Hz, 2H, Ar–H), 7.83–7.78 (m, 6H, Ar–H),
7.65–7.16 (m, 15H, Ar–H), 5.87–5.84 (m, 1H), 5.75–
5.65 (m, 3H), 5.42 (br s, 1H, H-6), 5.20 (s, 1H, H-10),
4.57–4.52 (m, 1H), 4.45–4.40 (m, 1H), 4.14 (br s, 2H),
3.97 (d, J = 4.8 Hz, 1H), 3.91–3.84 (m, 2H), 3.73–3.66
(m, 2H), 3.51–3.47 (m, 1H), 3.43–3.36 (m, 1H), 2.64–
2.60 (m, 1H), 2.44–2.26 (m, 3H), 1.37 (d, J = 5.1Hz,
3H, Rha–CH3), 1.22 (s, 9H, TBDPS–(CH3)3), 0.98 (d,
J = 6.9 Hz, 3H, H-21), 0.94 (s, 3H, H-19), 0.79 (br s,
6H, H-18, H-27); 13C NMR (75 MHz, CDCl3): d