C.-C. Zou et al. / Carbohydrate Research 338 (2003) 721–727
725
chromatography (10:15:1 petroleum ether–EtOAc)
gave 10 (252 mg, 91%) as a white solid: mp 156–
158 °C; [h]2D5 +19.2° (c 1.0, CHCl3); 1H NMR (300
MHz, CDCl3): l 8.09–7.24 (m, 20 H, HꢀOBz and
HꢀPh), 5.83 (dd, 1 H, 3.5, 10.0 Hz, H-3¦), 5.76 (dd, 1
H, 2.0, 3.5 Hz, H-2¦), 5.68 (t, 1 H, 10.0 Hz, H-4¦), 5.64
(d, 1 H, 2.0 Hz, H-1¦), 5.53 (s, 1 H, HꢀCHꢀPh), 5.49
(d, 1 H, 4.5 Hz, H-6), 4.74 (m, 1 H, H-5¦), 4.72 (d, 1 H,
8.0 Hz, H-1%), 4.43 (m, 1 H, H-16), 4.35 (dd, 8.0, 9.5
Hz, H-2%), 4.05 (t, 1 H, H-3%), 3.82–3.76 (m, 2 H,
H-6%a,b), 3.67 (m, 1 H, H-3), 3.56–3.36 (m, 4 H, H-4%,
H-5%, H-26a,b), 1.37 (d, 3 H, 6.5 Hz, H-6¦), 0.99 (d, 3
H, 7.0 Hz), 0.95 (s, 3 H), 0.80 (d, 3 H, 6.0 Hz), 0.78 (s,
3 H); 13C NMR (125 MHz, CDCl3): l 166.0, 165.9,
165.8, 140.3, 137.2, 133.6, 133.5, 133.3, 130.2 (2C),
130.0 (2C), 129.9 (2C), 129.7, 129.6, 129.5, 129.4, 128.8
(2C), 128.6 (2C), 128.5 (2C), 128.4 (2C), 126.5 (2C),
122.4, 109.5, 102.1, 100.8, 97.7, 81.0, 80.8, 79.9, 77.5,
75.4, 72.2, 70.8, 70.3, 68.9, 66.9, 66.1, 62.3, 56.7, 50.2,
41.8, 40.5, 39.9, 39.1, 37.4, 37.1, 32.4, 32.1, 31.7, 31.6,
30.5, 29.9, 29.0, 21.0, 19.5, 17.7, 17.4, 16.5, 14.8;
FABMS (m/z): 1123.4 [M+1], 1035.6, 459.1, 397.2;
Anal. Calcd for C67H78O15: C, 71.63; H, 7.00. Found:
C, 71.34; H, 7.19.
129.8 (2C), 129.7 (2C), 129.5, 129.3, 129.2, 129.1, 128.5
(2C), 128.4 (2C), 128.3 (2C), 128.2 (2C), 126.1 (2C),
122.3, 109.3, 100.4, 100.3, 99.1, 97.2, 80.9, 80.8, 79.3,
78.8, 77.3, 76.0, 73.0, 71.7, 71.6, 71.5, 70.3, 70.1, 68.8,
68.7, 66.8, 66.7, 66.2, 62.1 (2C), 56.4, 50.0, 41.6, 40.3,
39.7, 38.7, 37.2, 36.8, 32.2, 31.9, 31.5, 31.4, 30.3, 29.9,
28.8, 20.8, 20.7, 20.6, 20.5, 19.3, 17.3, 17.1, 16.3, 14.5;
FABMS (m/z): 1475.8 [M+Na], 514.0, 459.1, 397.3;
Anal. Calcd for C81H96O24: C, 66.92; H, 6.66. Found:
C, 66.65; H, 6.45.
3.9. Preparation of diosgenyl a-
2)-[b- -glucopyranosyl-(13)]-b-
(gracillin, 2)
L
-rhamnopyranosyl-(1
D
D-glucopyranoside
A solution of 12 (145 mg, 100 mmol) in 80% HOAc (10
mL) was stirred at 70 °C for 2 h, then concentrated to
dryness under reduced pressure. The residue was redis-
solved in 1:1 MeOH–CH2Cl2 (5 mL) at rt, and MeONa
was then added (0.05 mL 1 M in MeOH). The mixture
was stirred overnight, neutralized with Dowex-50 (H+)
resin and filtered, and the filtrate was then concen-
trated. Purification of the product by column chro-
matography (10:18:1 CH2Cl2–MeOH) gave 2 (70
mg, 81%) as a white solid: mp \250 °C, lit.2 298–
302 °C; [h]2D5 −83.4° (c 1.0, Py), lit.2 −86.2° (c 0.12,
DMF); 13C NMR (125 MHz, Py-d5): l 140.8, 121.8,
109.3, 104.5, 102.2, 100.0, 89.5, 81.1, 78.7, 78.5, 77.9,
77.8, 77.1, 75.0, 74.1, 72.8, 72.5, 71.5, 69.6, 69.5, 66.9,
62.9, 62.5 (overlap, 2C), 56.7, 50.3, 42.0, 40.5, 39.9,
38.7, 37.5, 37.2, 32.3, 32.2, 31.9, 31.7, 30.6, 30.1, 29.3,
21.1, 19.4, 18.7, 17.3, 16.3, 14.5; FABMS (m/z): 885
[M+1], 723, 631, 577, 415, 397.
3.8. Diosgenyl 2,3,4-tri-O-benzoyl-a-
pyranosyl-(12)-[2,3,4,6-tetra-O-acetyl-b-
pyranosyl-(13)]-4,6-O-benzylidene-b-
L
-rhamno-
-gluco-
-glucopyran-
D
D
oside (12)
,
To a solution of 10 (42 mg, 37 mmol) and 4 A molecu-
lar sieves (100 mg) in dry CH2Cl2 (5 mL) under Ar at
−78 °C, was added BF3·Et2O (0.02 mL, 170 mmol),
then a solution of 11 (55 mg, 111 mmol) in dry CH2Cl2
(1 mL). The mixture was naturally warmed to rt and
stirred for 4 h, neutralized with Et3N and filtered, and
then the filtrate was concentrated. Purification of the
product by column chromatography (5:13:1
petroleum ether–EtOAc) gave 12 (45 mg, 83%) as a
white solid: mp 196–198 °C; [h]2D5 +5.2° (c 0.9,
3.10. Diosgenyl 2,3,4-tri-O-benzoyl-a-L-rhamnopyran-
osyl-(12)-3-O-acetyl-4,6-O-benzylidene-b-D-gluco-
pyranoside (13)
To a solution of 10 (99 mg, 88 mmol) in dry Py (2 mL)
was added Ac2O (1 mL) at rt. The mixture was stirred
for overnight and concentrated to dryness. Purification
of the product by column chromatography (8:16:1
petroleum ether–EtOAc) gave 13 (102 mg, 98%) as a
white solid: mp 213–215 °C; [h]2D5 +29.6° (c 1.0,
1
CHCl3); H NMR (500 MHz, CDCl3): l 8.15–7.24 (m,
20 H, HꢀOBz and H-Ph), 5.77 (dd, 1 H, 3.5, 10.0 Hz,
H-3¦), 5.72 (dd, 1 H, 1.5, 3.5 Hz, H-2¦), 5.69 (t, 1 H,
10.0 Hz, H-4¦), 5.52 (brs, 2 H, overlap, HꢀCHꢀPh,
H-1¦), 5.48 (d, 1 H, 4.5 Hz, H-6), 5.30 (t, 1 H, 9.5 Hz,
H-3§), 5.02–5.49 (m, 3 H, H-1§, H-2§, H-4§), 4.82 (m,
1 H, H-5¦), 4.68 (d, 1 H, 8.0 Hz, H-1%), 4.42 (m, 1 H,
H-16), 4.33 (m, 1 H, H-5§), 4.20–4.09 (m, 2 H, H-
6§a,b), 4.02 (m, 1 H, 10.0 Hz, H-3%), 3.88 (m, 1 H,
H-4%), 3.79 (m, 1 H, H-2%), 3.68–3.64 (m, 3 H, H-3,
H-6%a,b), 3.40–3.36 (m, 3 H, H-5%, H-26a,b), 1.99, 1.98,
1.87, 1.73 (s each, 3 H each, HꢀOAc), 1.35 (d, 3 H, 6.0
Hz, H-6¦), 0.98 (d, 3 H, 7.0 Hz), 0.93 (s, 3 H), 0.79 (d,
3 H, 6.0 Hz), 0.78 (s, 3 H). 13C NMR (125 MHz,
CDCl3): l 170.7, 169.9, 169.6, 169.2, 165.8, 165.7,
165.4, 140.0, 137.2, 133.4, 133.2, 133.1, 130.1 (2C),
1
CHCl3); H NMR (500 MHz, CDCl3): l 8.10–7.25 (m,
20 H, HꢀOBz and HꢀPh), 5.81 (dd, 1 H, 3.5, 10.0 Hz,
H-3¦), 5.70 (dd, 1 H, 2.0, 3.5 Hz, H-4¦), 5.52 (t, 1 H, 9.5
Hz, H-3%), 5.50–5.45 (m, overlap, 3 H, 10.0 Hz, H-6,
H-1¦, H-2¦), 5.34 (s, 1 H, HꢀCHꢀPh), 4.79 (d, 1 H, 8.0
Hz, H-1%), 4.74 (m, 1 H, H-5¦), 4.43 (m, 1 H, H-16),
4.35 (dd, 8.0, 9.5 Hz, H-2%), 3.88–3.67 (m, 3 H, H-3,
H-26a,b), 3.62–3.54 (m, 2 H, H-6%a,b), 3.48 (m, 1 H,
H-5%), 3.39 (t, 1 H, 10.0 Hz, H-4%), 2.19 (s, 3 H,
HꢀOAc), 1.34 (d, 3 H, 6.5 Hz, H-6¦), 0.97 (d, 3 H, 7.0
Hz), 0.90 (s, 3 H), 0.79 (d, 3 H, 6.5 Hz), 0.77 (s, 3 H);
Anal. Calcd for C69H80O16: C, 71.11; H, 6.92. Found:
C, 71.36; H, 6.65.