L. Hu et al. / Bioorg. Med. Chem. 8 (2000) 1515±1521
1519
(
(
KBr) nmax 3539, 3502, 1793, 1776 cm 1; 1H NMR
�
89.2%) after ¯ash chromatography (cyclohexane:ace-
�
1 1
DMSO-d , 400 MHz) d 1.02 (9H, s, t-Bu), 1.11 (3H, d,
tone 2:1). 12: IR (KBr) nmax 3419, 1786, 1691 cm ; H
6
J=7.1 Hz, H-16), 1.71 (1H, dd, J=14.2, 4.1 Hz, H-8),
NMR (DMSO-d , 400 MHz) d 1.05 (9H, s, t-Bu), 1.12
6
1
.89 (1H, ddd, J=14.1, 13.6, 4.1 Hz, H-7a), 2.13 (1H,
(3H, d, J=7.0 Hz, H-16), 1.78 (1H, dd, J=14.2, 4.1 Hz,
H-8), 1.92 (1H, ddd, J=14.1, 13.6, 4.1 Hz, H-7a), 2.18
(1H, dd, J=13.6, 4.3 Hz, H-7b), 2.83 (1H, q, J=7.1 Hz,
H-14), 4.11 (1H, dd, J=7.7, 3.0 Hz, H-1b), 4.71 (1H, d,
dd, J=13.5, 4.2 Hz, H-7b), 2.84 (1H, q, J=7.1 Hz,
H-14), 4.12 (1H, d, J=6.7 Hz, H-1b), 4.12 (1H, dd, J=
1
1.6, 4.8 Hz, CH CHCH -), 4.63 (1H, d, J=6.7 Hz,
2
2
H-2), 4.77 (1H, dd, J=12.9, 4.9 Hz, CH CHCH -),
2 2
J=7.7 Hz, H-2), 5.31 (1H, d, J=17.7 Hz, PhCOCH -),
2
5
.09 (1H, s, H-10), 5.16 (1H, d, J=10.5 Hz, CH
5.38 (1H, s, H-10), 5.40 (1H, d, J=3.7 Hz, H-6), 5.65
(1H, d, J=17.6 Hz, PhCOCH -), 5.78 (1H, d, J=3.2 Hz,
2
CHCH -), 5.29 (1H, d, J=17.5 Hz, CH CHCH -),
2
2
2
2
5
.33 (1H, d, J=3.7 Hz, H-6), 5.95 (1H, m, CH
1-OH), 6.25 (1H, s, H-12), 6.56 (1H, s, 3-OH), 7.59 (2H,
d, J=7.6 Hz, PhCOCH -), 7.73 (1H, t, J=7.5 Hz,
2
1
CHCH -), 6.13 (1H, s, H-12), 6.50 (1H, s, 3-OH). H
2
2
1
NMR (acetone-d , 400 MHz) d 1.17 (9H, s, t-Bu), 1.26
PhCOCH -), 7.92 (2H, d, J=8.1 Hz, PhCOCH -). H
2
6
2
(
3H, d, J=7.1 Hz, H-16), 1.94 (1H, dd, J=14.4, 4.6 Hz,
NMR (acetone-d , 400 MHz) d 1.18 (9H, s, t-Bu), 1.27
6
H-8), 2.09 (1H, m, H-7a), 2.28 (1H, dd, J=13.6, 4.6 Hz,
H-7b), 3.03 (1H, q, J=7.1 Hz, H-14), 4.25 (1H, d,
J=7.8 Hz, H-1b), 4.33 (1H, dd, J=11.7, 6.3 Hz,
CH CHCH -), 4.68 (1H, d, J=7.8 Hz, H-2), 4.92 (1H,
(3H, d, J=7.0 Hz, H-16), 1.99 (1H, dd, J=13.6, 4.3 Hz,
H-8), 2.11 (1H, ddd, J=14.1, 13.6, 4.1 Hz, H-7a), 2.28
(1H, dd, J=13.6, 4.3 Hz, H-7b), 3.04 (1H, q, J=7.0 Hz,
H-14), 4.34 (1H, d, J=7.7 Hz, H-1), 4.72 (1H, d,
2
2
dd, J=11.7, 6.3 Hz, CH CHCH -), 5.25 (1H, s, H-10),
J=7.7 Hz, H-2), 5.48 (1H, d, J=17.3 Hz, PhCOCH -),
2
2
2
5
1
6
.40 (1H, d, J=4.3 Hz, H-6), 5.42 (1H, dd, J=10.7,
.0 Hz, CH CHCH -), 6.08 (2H, m, CH CHCH -),
+
5.49 (1H, s, H-10), 5.51 (1H, d, J=4.0 Hz, H-6), 5.85
(1H, d, J=17.3 Hz, PhCOCH -), 6.23 (1H, s, H-12),
2
2
2
2
2
.18 (1H, s, H-12). HREIMS m/z 464.16803, C H O
7.59 (2H, d, J=7.8 Hz, PhCOCH -), 7.73 (1H, t, J=
2
23
28 10
requires 464.16825; EIMS m/z 464 [M] , 449, 421, 405,
7.8 Hz, PhCOCH -), 8.01 (2H, d, J=7.8 Hz, PhCOCH -).
2
2
3
87, 364, 335, 307, 221, 135, 113, 95, 69, 57.
HREIMS m/z 542.17820, C H O requires 542.17882;
28 30 11
EIMS m/z 542 [M] , 524, 498, 469, 451, 408, 379, 323,
294, 120, 105, 91, 77, 57.
+
10-O-Ethyloxycarbonylmethylginkgolide B (11) and 1-O-
ethyloxycarbonylmethylginkgolide B (23). Compounds
1 and 23 were prepared from 333 mg of ginkgolide B
and ethyl a-bromoacetate (467 mg) as described by the
preceding general procedure to obtain white solids 11
1
10-O-p-Methoxyphenacylginkgolide B (13). Compound
13 was prepared from 333 mg of ginkgolide B and
2-bromo-p-methoxyacetophenone (640 mg) as described
by the preceding general procedure to obtain white solid
13 (405 mg, 90.1%) after ¯ash chromatography (cyclo-
(
chromatography (cyclohexane:acetone 2:1). 11: IR
313 mg, 78.3%) and 23 (49 mg, 12.1%) after ¯ash
�
1 1
(
KBr) nmax 3481, 1784, 1743 cm ; H NMR (acetone-
d6, 400 MHz) d 1.16 (9H, s, t-Bu), 1.26 (3H, d, J=
.0 Hz, H-16), 1.28 (3H, t, J=7.1 Hz, CH CH2
hexane:acetone 2:1). 13: IR (KBr) n
3410, 1790,
max
�
1
1
1680, 1601 cm
; H NMR (acetone-d , 400 MHz) d
6
7
1.18 (9H, s, t-Bu), 1.27 (3H, d, J=7.0 Hz, H-16), 1.99
(1H, dd, J=14.2, 4.3 Hz, H-8), 2.08 (1H, ddd, J=14.1,
13.6, 4.1 Hz, H-7a), 2.28 (1H, dd, J=13.3, 4.4 Hz,
H-7b), 3.03 (1H, q, J=7.0 Hz, H-14), 3.92 (3H, s,
p-MeOC H COCH -), 4.34 (1H, d, J=7.8 Hz, H-1b),
3
OOCCH -), 1.96 (1H, ddd, J=14.3, 13.6, 4.2 Hz, H-7a),
2
2
3
.07 (1H, m, H-8), 2.28 (1H, dd, J=13.6, 4.4 Hz, H-7b),
.01 (1H, q, J=7.1 Hz, H-14), 4.27 (2H, q, J=7.1 Hz,
CH CH OOCCH -), 4.28 (1H, d, J=7.6 Hz, H-1b),
3
2
2
6
4
2
4.54 (1H, d, J=15.6 Hz, CH CH OOCCH -), 4.67 (1H,
d, J=7.7 Hz, H-2), 4.98 (1H, d, J=15.7 Hz, CH CH2
4.71 (1H, d, J=7.8 Hz, H-2), 5.41 (1H, d, J=16.9 Hz,
3
2
2
p-MeOC H COCH -), 5.47 (1H, s, H-10), 5.51 (1H, d,
6
3
4
2
OOCCH -), 5.44 (1H, d, J=3.9 Hz, H-6), 5.38 (1H, s,
2
J=3.9 Hz, H-6), 5.78 (1H, d, J=17.1 Hz, p-MeOC H
6 4-
H-10), 6.19 (1H, s, H-12). HREIMS m/z 510.17365,
+
C H O requires 510.17373; EIMS m/z 510 [M] ,
COCH -), 6.22 (1H, s, H-12), 7.09 (2H, d, J=8.8 Hz,
2
p-MeOC H COCH -), 7.98 (2H, d, J=8.7 Hz, p-MeOC
6
2
4
30 12
6
4
2
4
1
1
92, 437, 362, 323, 259, 95, 57. 23: IR (KBr) n
3440,
H COCH -). HREIMS m/z 572.18986, C H O
4 2 29 32 12
requires 572.18938; EIMS m/z 572 [M] , 554, 528, 499,
443, 408, 388, 350, 165, 150, 135, 77, 57.
max
�
1
1
+
794, 1730 cm
.16 (9H, s, t-Bu), 1.25 (3H, d, J=7.0 Hz, H-16), 1.25
;
H NMR (acetone-d , 400 MHz) d
6
(
3H, t, J=7.1 Hz, CH CH OOCCH -), 2.16 (1H, ddd,
3 2 2
J=14.3, 13.6, 4.2 Hz, H-7a), 2.24 (1H, dd, J=13.6,
.4 Hz, H-7b), 2.24 (1H, m, H-8), 3.05 (1H, q,
J=7.0 Hz, H-14), 4.19 (1H, d, J=5.9 Hz, H-1b), 4.20
2H, q, J=7.1 Hz, CH CH OOCCH -), 4.33 (1H, d,
10-O-Benzylginkgolide B (14). Compound 14 was pre-
pared from 333 mg of ginkgolide B and benzyl chloride
(355 mg) as described by the preceding general pro-
cedure to obtain white solid 14 (264 mg, 65.3%) after
¯ash chromatography (cyclohexane:acetone 2:1). 14: IR
4
(
3
2
2
J=5.1 Hz, H-2), 4.33 (1H, d, J=15.9 Hz, CH CH2
3
�
1
1
OOCCH -), 4.95 (1H, d, J=16.1 Hz, CH CH2
2
(KBr) nmax 3529, 1780 cm
;
H NMR (DMSO-d6,
3
OOCCH -), 5.23 (1H, s, H-10), 5.51 (1H, d, J=3.9 Hz,
2
400 MHz) d 1.01 (9H, s, t-Bu), 1.12 (3H, d, J=7.1 Hz,
H-16), 1.73 (1H, dd, J=14.2, 4.3 Hz, H-8), 1.87 (1H,
ddd, J=14.1, 13.6, 4.1 Hz, H-7), 2.13 (1H, dd, J=13.3,
4.4 Hz, H-7b), 2.87 (1H, q, J=7.0 Hz, H-14), 4.15 (1H,
dd, J=6.7, 3.2 Hz, H-1b), 4.62 (1H, d, J=6.7 Hz, H-2),
4.67 (1H, d, J=11.3 Hz, C H CH -), 4.79 (1H, d,
H-6), 6.08 (1H, s, H-12). HREIMS m/z 510.17370,
+
C H O requires 510.17373; EIMS m/z 510 [M] ,
2
4
30 12
495, 437, 363, 333, 259, 231, 163, 83, 57.
10-O-Phenacylginkgolide B (12). Compound 12 was
6
5
2
prepared from 333 mg of ginkgolide B and 2-chloro-
acetophenone (433 mg) as described by the preceding
general procedure to obtain white solid 12 (380 mg,
J=3.2 Hz, 1-OH), 5.25 (1H, s, H-10), 5.31 (1H, d,
J=3.7 Hz, H-6), 5.35 (1H, d, J=11.4 Hz, C H CH -),
6.19 (1H, s, H-12), 6.49 (1H, s, 3-OH), 7.36 (5H, m,
6
5
2