K. Ohmori et al. / Tetrahedron 60 (2004) 1365–1373
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4.3.1. Silyl ether 23. To a solution of alcohol 22 (1.014 g,
1.56 mmol) in DMF (3.3 mL) was added imizazole
(321 mg, 4.71 mmol) and TBDMSCl (352 mg, 2.34 mmol)
at 25 8C. After stirring for 12 h at this temperature, the
reaction was stopped by adding aqueous pH 7 phosphate
buffer. The mixture was extracted with Et2O (£3). The
combined organic extracts were washed with brine, and
dried (Na2SO4), concentrated in vacuo. The residue was
purified by flash column chromatography (hexanes/EtOAc,
95:5) to give 23 (1.07 mg, 90%) as colorless oil.
Et2O (£3), and the combined organic extracts were succes-
sively washed with saturated aqueous NaHCO3, brine, and
dried (Na2SO4), concentrated in vacuo. The residue was
purified by preparative TLC (benzene/EtOAc, 98:2) to give25
(12.6 mg, 32%) as white solid.
Compound 25. [a]2D0 þ19.7 (c 1.02, CHCl3); IR (KBr) 3065,
3030, 2925, 2855, 1695, 1610, 1575, 1515, 1455, 1430,
1375, 130.5, 1260, 1210. 1160, 1115, 1025, 875, 840, 780,
1
735, 695 cm21; H NMR (300 MHz, CDCl3) d 20.31 (s,
3H), 0.13 (s, 3H), 0.63 (s, 9H), 4.30 (d, 1H, J¼11.2 Hz),
4.99 (s, 2H), 5.03 (d, 1H, J¼11.2 Hz), 5.14 (d, 1H,
J¼12.0 Hz), 5.19 (s, 2H), 5.20 (d, 1H, J¼12.0 Hz), 5.21
(s, 2H), 6.16 (d, 1H, J¼2.0 Hz), 6.19 (d, 1H, J¼2.0 Hz),
6.94 (d, 1H, J¼8.3 Hz), 6.99 (dd, 1H, J¼8.3, 2.0 Hz), 7.11
(d, 1H, J¼2.0 Hz), 7.28–7.53 (m, 20H); 13C NMR
(75 MHz, CDCl3) d 26.1, 24.2, 18.3, 25.5, 70.2, 70.4,
71.3, 76.0, 76.6, 83.7, 94.6, 95.7, 105.0, 114.1, 115.0, 121.2,
126.4, 127.2. 127.3, 127.5, 127.8,128.3, 128.5, 128.7, 130.9,
135.7, 136.6, 137.10, 137.13, 149.0, 149.3, 160.9, 164.1,
164.6, 189.6. Anal. Calcd for C49H50O7Si: C, 75.55; H,
6.47. Found C, 75.26, H, 6.71.
Compound 23. [a]2D0 þ21.9 (c 1.00, CHCl3); IR (neat) 3030,
2855, 1620, 1595, 1500, 1455, 1430, 1375, 1260, 1215,
1150, 1125, 1050, 1030 cm21; 1H NMR (300 MHz, CDCl3)
d 20.48 (s, 3H), 20.18 (s, 3H), 0.72 (s, 9H), 2.62 (dd, 1H,
J¼16.4, 9.5 Hz), 3.10 (dd, 1H, J¼16.4, 5.8 Hz), 3.89 (ddd,
1H, J¼9.5, 9.0, 5.8 Hz), 4.56 (d, 1H, J¼9.0 Hz), 4.95 (d,
1H, J¼11.7 Hz), 4.99 (d, 1H, J¼11.7 Hz), 5.04 (d, 1H,
J¼11.7 Hz), 5.08 (d, 1H, J¼11.9 Hz), 5.12 (d, 1H, J¼
11.9 Hz), 5.159 (d, 1H, J¼10.3 Hz), 5.162 (d, 1H,
J¼11.9 Hz), 5.19 (d, 1H, J¼10.3 Hz), 6.20 (d, 1H,
J¼2.2 Hz), 6.23 (d, 1H, J¼2.2 Hz), 6.92 (s, 2H), 7.05 (s,
1H), 7.27–7.48 (m, 20H); 13C NMR (75 MHz, CDCl3) d
25.2, 24.9, 17.8, 25.6, 30.3, 69.4, 69.9, 70.1, 71.2, 71.4,
82.1, 93.8, 94.3, 102.9, 114.2, 115.1, 121.1, 126.8, 127.3,
127.5, 127.72, 127.76, 127.8, 127.9, 128.42, 128.46, 128.50,
128.6, 132.7, 136.9, 137.16, 137.26, 137.29, 147.7, 149.0,
155.6, 157.5, 158.7. Anal. Calcd for C49H52O6Si: C, 76.93;
H, 6.85. Found C, 76.92, H, 7.08.
4.3.4. Alcohol 8. To a solution of 25 (8.6 mg, 0.011 mmol)
in EtOH (0.5 mL) was added PPTS (5 mg) at 25 8C. After
stirring for 66 h, the reaction was stopped by adding water.
The mixture was extracted with EtOAc (£3). The combined
organic extracts were washed with brine, and dried
(Na2SO4), concentrated in vacuo. The residue was purified
by preparative TLC (benzene/EtOAc, 95:5) to give 8
(4.5 mg, 60%) as white solid.
4.3.2. Alcohol 24. To a solution of 23 (35.8 mg,
0.0478 mmol) in CH2Cl2 (9.0 mL) was added DDQ
(80.9 mg, 0.356 mmol) and H2O (0.45 mL, 25.0 mmol) at
25 8C. After stirring for 1.5 h at this temperature, the
reaction was stopped by adding water. The mixture was
extracted with Et2O (£3). The combined organic extracts
were successively washed with saturated aqueous NaHCO3
and brine, and dried (Na2SO4), concentrated in vacuo. The
residue was purified by preparative TLC (benzene/EtOAc,
95:5) to give 24 (106 mg, 76%) as white solid.
[a]2D1 29.0 (c 0.46, CHCl3); mp 193.5–194.2 8C; IR (KBr)
3465, 3035, 2925, 1675, 1610, 1580, 1515, 1440, 1375, 1310,
1260, 1215, 1170, 1135, 1120, 1010, 810, 695 cm21; 1H NMR
(500 MHz, CDCl3) d 4.06 (br s, 1H), 4.42 (d, 1H, J¼12.2 Hz),
4.95 (d, 1H, J¼12.2 Hz), 5.05 (s, 2H), 5.10–5.25 (m, 6H), 6.19
(d, 1H, J¼2.2 Hz), 6.26 (d, 1H, J¼2.2 Hz), 7.00 (d, 1H,
J¼8.3 Hz), 7.09 (dd, 1H, J¼8.3, 1.9 Hz), 7.18 (d, 1H,
J¼1.9 Hz), 7.27–7.58 (m, 20H); 13C NMR (125 MHz,
CDCl3) d 70.4, 70.5, 71.2, 71.4, 72.7, 83.1, 94.8, 95.2, 103.4,
114.1, 114.7, 121.0, 126.6, 127.2, 127.5, 127.6, 127.8, 127.85,
127.92, 128.48, 128.51, 128.7, 128.8, 129.6, 135.5, 136.0,
137.1, 137.2, 149.1, 149.8, 160.9, 164.8, 165.9, 190.6. Anal.
Calcd for C43H36O7: C, 77.69; H, 5.46. Found C, 77.41; H, 5.73.
Compound 24. [a]2D1 þ31.4 (c 1.02, CHCl3); IR (neat) 3540,
3060, 3030, 2940, 2855, 1620, 1590, 1515, 1455, 1430,
1375, 1310, 1265, 1200, 1150, 1120, 1090, 1060, 1030,
1
910 cm21; H NMR (300 MHz, CDCl3) d 20.56 (s, 3H),
20.14 (s, 3H), 0.76 (s, 9H), 2.91 (s, 1H), 3.86 (dd, 1H,
J¼9.8, 3.4 Hz), 4.93–5.00 (m, 4H), 5.09–5.21 (m, 6H),
6.16 (d, 1H, J¼2.0 Hz), 6.24 (d, 1H, J¼2.0 Hz), 6.94 (s,
2H), 7.08 (s, 1H), 7.29–7.48 (m, 20H); 13C NMR (75 MHz,
CDCl3) d 25.7, 25.1, 17.9, 25.7, 62.3, 70.0, 71.1, 71.3,
72.7, 75.8, 94.3, 94.3, 94.4, 104.3, 114.3, 115.0, 121.4,
126.7, 127.2, 127.5, 127.6, 127.7, 127.8, 128.0, 128.4,
128.5, 129.2, 131.9, 136.5, 137.0, 137.1, 137.2, 148.8,
149.0, 156.1, 158.8, 160.7. Anal. Calcd for C49H52O7Si: C,
73.35; H, 6.71. Found C, 75.18, H, 6.96.
4.3.5. Preparation of alcohol 9. To a solution of 22 (56 mg,
0.086 mmol) in CHCl3 (10 mL) was added MeOH (0.5 mL)
and DDQ (39 mg, 0.017 mmol) at 25 8C. After stirring for 4 h,
the mixture was diluted with water and Et2O, and the products
were extracted with Et2O (£4). The combined organic extracts
were successively washed with saturated aqueous NaHCO3,
brine, and dried (Na2SO4), concentrated in vacuo. The residue
was purified by preparative TLC (benzene/EtOAc, 95:5) to
give 9 (45 mg, 79%) as white solid.
4.3.3. Ketone 25. Toa solutionof24(39.8 mg, 0.0510 mmol)
in CH2Cl2 (1.0 mL) was added N-methyl morpholine N-oxide
(6.5 mg 0.081 mmol) and TPAP (1.6 mg, 0.0046 mmol) at
25 8C. After stirring for 10 h, an additional portion of TPAP
(1.6 mg, 0.0046 mmol) was added, and stirred for 4.5 h. The
mixture was diluted with CH2Cl2, filtered through the Celite
pad. The filtrate was concentrated in vacuo, and extracted with
Compound 9. [a]2D1 253.1 (c 1.02, CHCl3); mp 142–144 8C;
IR (KBr) 3415, 3030, 2910, 1620, 1590, 1515, 1500, 1430,
1380, 1260, 1220, 1165, 1120, 1070, 1030, 815, 735,
695 cm21 1H NMR (300 MHz, CDCl3) d 2.37 (d, 1H,
;
J¼9.0 Hz), 3.50 (s, 6H), 3.89 (ddd, 1H, J¼10.3, 9.0, 3.7 Hz),
4.73 (d, 1H, J¼3.7 Hz), 4.94 (d, 1H, J¼10.3 Hz), 4.99 (s, 2H),
5.01 (d, 1H, J¼11.2 Hz), 5.07 (d, 1H, J¼11.2 Hz), 5.16 (s,