4214
T. Murata et al. / Tetrahedron: Asymmetry 9 (1998) 4203–4217
were removed by filtration through a Celite pad and washed with EtOAc. The combined filtrate and
washing were concentrated in vacuo and the residue was purified by column chromatography on silica gel
(EtOAc:hexane, 1:18) providing 37.7 mg (90%) of 23 as a colorless oil: TLC, Rf 0.47 (EtOAc:hexane,
24
1
1:4); [α]D +52.1 (c 1.09, CHCl3); IR (neat) 3500, 2990, 1640 cm−1; H NMR (270 MHz) δ 1.19
(d, J=7.3 Hz, 3 H, CH3 at C-40), 1.32, 1.37, 1.43, 1.48 (4s, 3 H×4, 4×C(CH3)2), 1.25–1.85 (m, 8 H,
cyclohexyl ring protons), 1.86–2.01 (m, 1 H, OH), 3.87–3.96 (m, 1 H, H-200), 4.10–4.23 (m, 3 H, H-200,
H-100, H-5), 4.27–4.34 (br s, 1 H, H-20), 5.20 (d, J=3.7 Hz, 1 H, H-3), 5.23 (dd, J=11.7, 1.5 Hz, 1 H,
–CH=CH2), 5.42 (dd, J=18.0, 1.5 Hz, 1 H, –CH=CH2), 5.68 (d, J=3.7 Hz, 1 H, H-2), 6.10 (dd, J=18.0,
11.7 Hz, 1 H, –CH=CH2); 13C NMR (75 MHz) δ 17.3, 20.9, 25.5, 26.1, 26.4, 26.5, 27.0, 32.2, 40.1,
44.1, 57.4, 69.1, 69.3, 73.6, 84.8, 84.9, 104.8, 109.6, 110.9, 116.3, 137.6; HRMS calcd for C21H34O6
(M+) m/z 382.2355, found 382.2334.
3.11. Acetylation of 23
Compound 23 (37.2 mg, 0.10 mmol) was acetylated with Ac2O (0.5 ml) in pyridine (0.5 ml) at 50°C
for 84 h. Concentration of the reaction mixture and purification of the residue by column chromatography
on silica gel (EtOAc:hexane, 1:17) provided 39.1 mg (95%) of 24 as a colorless oil: TLC, Rf 0.49
(EtOAc:hexane, 1:4); [α]D +58.4 (c 0.30, CHCl3); IR (neat) 2985, 2940, 1740, 1640 cm−1; 1H NMR
23
(270 MHz) δ 1.06 (d, J=7.3 Hz, 3 H, CH3 at C-40), 1.32, 1.38, 1.42, 1.47 (4s, 3 H×4, 4×C(CH3)2),
1.35–2.04 (m, 8 H, cyclohexyl ring protons), 2.06 (s, 3 H, OC(O)CH3), 3.87–3.95 (m, 1 H, H-200),
4.08–4.24 (m, 3 H, H-200, H-100, H-5), 5.04 (d, J=3.7 Hz, 1 H, H-3), 5.22 (d, J=11.4, 1.5 Hz, 1 H,
–CH=CH2), 5.27 (br s, 1 H, H-20), 5.35 (dd, J=18.0, 1.5 Hz, 1 H, –CH=CH2), 5.70 (d, J=3.7 Hz, 1 H,
H-2), 5.85 (dd, J=18.0, 11.4 Hz, 1 H, –CH=CH2); 13C NMR (75 MHz) δ 18.2, 20.0, 21.5, 25.5, 25.7,
26.3, 26.4, 27.0, 31.5, 35.4, 42.6, 57.1, 69.3, 72.8, 73.5, 84.3, 85.1, 105.0, 109.7, 110.9, 117.2, 136.3,
169.8. Anal. calcd for C23H36O7: C, 65.07; H, 8.55. Found: C, 65.34; H, 8.79.
3.12. DIBAL-H
reduction
of
22.
(2R,3R,4S,5S)-2,3-(Isopropylidene)dioxy-5-[(1R)-1,2-
(isopropylidene)dioxyethyl]-4-[(1S,2S,4S)- 25 and (1S,2R,4S)-2-hydroxy-4-vinylcyclohexyl]-4-
vinyltetrahydrofuran 26
As described for 21, 47.7 mg (0.12 mmol) of 22 in CH2Cl2 (1 ml) was treated with DIBAL-H (0.37
mmol) at −78°C for 60 min. After workup and purification by column chromatography on silica gel
(EtOAc:hexane, 1:20), 40.0 mg (83%) of 25 and 4.5 mg (9%) of 26 were obtained. 25: colorless oil; TLC,
Rf 0.40 (EtOAc:hexane, 1:4); [α]D22 +47.6 (c 0.86, CHCl3); IR (neat) 3500, 2990, 2920, 1640 cm−1; 1H
NMR (270 MHz) δ 1.31, 1.38, 1.43, 1.47 (4s, 3 H×4, 4×C(CH3)2), 1.25–2.00 (m, 8 H, cyclohexyl ring
protons), 2.43–2.54 (m, 1 H, OH), 3.85–3.97 (m, 1 H, H-200), 4.10–4.24 (m, 3 H, H-200, H-100, H-5),
4.33–4.38 (br s, 1 H, H-20), 5.06 (ddd, J=10.6, 1.8, 1.8 Hz, 1 H, –CH=CH2), 5.13 (ddd, J=17.2, 1.8,
1.8 Hz, 1 H, –CH=CH2), 5.20 (d, J=3.7 Hz, 1 H, H-3), 5.24 (dd, J=11.4, 1.8 Hz, 1 H, –CH=CH2), 5.43
(dd, J=18.0, 1.8 Hz, 1 H, –CH=CH2), 5.65 (d, J=3.7 Hz, 1 H, H-2), 6.09 (dd, J=18.0, 11.4 Hz, 1 H,
–CH=CH2), 6.29 (ddd, J=17.2, 10.6, 6.6 Hz, 1 H, –CH=CH2); 13C NMR (75 MHz) δ 18.0, 25.6, 26.4,
26.5, 27.1, 29.9, 34.7, 39.2, 43.8, 57.4, 69.2, 69.4, 73.6, 84.6, 84.8, 104.7, 109.6, 110.9, 113.5, 116.6,
137.4, 143.9; HRMS calcd for C22H34O6 (M+) m/z 394.2355, found 394.2372. 26: colorless oil; TLC,
23
Rf 0.42 (EtOAc:hexane, 1:4); [α]D +35.0 (c 0.20, CHCl3); IR (neat) 3500, 2980, 2925, 1640 cm−1
;
1H NMR (270 MHz) δ 1.32, 1.37, 1.43, 1.48 (4s, 3 H×4, 4×C(CH3)2), 1.50–1.90, 1.90–2.10, 2.25–2.50
(3m, total 9H, cyclohexyl ring protons, OH), 3.87–3.96 (m, 1 H, H-200), 4.09–4.25 (m, 3 H, H-200, H-100,
H-5), 4.34–4.42 (m, 1 H, H-20), 4.92 (ddd, J=10.6, 1.5, 1.5 Hz, 1 H, –CH=CH2), 4.98 (ddd, J=17.2, 1.5,