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J.G. Cui et al. / Steroids 67 (2002) 1015–1019
2.6. Cholest-5-en-3β-ol-24-one (8)
PtO2 (7 mg) was added to a solution of 7 (80 mg;
0.18 mmol) in 15 ml of EtOAc. Hydrogen was passed into
the stirred mixture at room temperature. After 30 min, the
reaction was stopped, and the mixture was filtered. The sol-
vent was removed in vacuum and the resulting white solid
was recrystallized from acetone to give 79 mg of 8 as white
needles (98%), mp 136–137 ◦C. IR (KBr) ν: 3416, 1707,
Scheme 1.
1640, 1581, 1461, 1377, 1243, 1103, 1053, 1025, 955 cm−1
.
1H NMR (CDCl3, 500 Hz) δ: 0.68 (s, 3H, 18-CH3), 0.92
(d, 3H, J = 7.0 Hz, 21-CH3), 1.01 (s, 3H, 19-CH3), 1.09
(d, 6H, J = 7.0 Hz, 26-CH3 and 27-CH3), 2.61 (m, 1H,
J = 7.0 Hz, 25-CH), 3.53 (tt, 1H, J = 12.0 and 5.5 Hz,
3-CH), 5.35 (dd, 1H, J = 3.0 and 2.5 Hz, 6-CH).
2.3. 5α,6β-Dibromostigmast-22-en-3β-
(2-tetrahydropyranyl)ether (5)
White solid (yield of 76%), mp 117–118 ◦C. IR (KBr)
ν: 1651, 1461, 1377, 1152, 1053, 969, 568 cm−1. 1H NMR
(CDCl3, 90 MHz) δ: 0.70 (s, 3H, 18-CH3), 0.79 (d, 3H, J =
6.4 Hz, 26-CH3 or 27-CH3), 0.81 (t, 3H, J = 7.6 Hz, 29-
CH3), 0.84 (d, 3H, J = 6.4 Hz, 26-CH3 or 27-CH3), 1.01 (s,
3H, 19-CH3), 1.02 (d, 3H, J = 6.7 Hz, 21-CH3), 3.52 (bm,
2H, THP 6-CH2), 4.30–4.56 (bm, 1H, 3-CH), 4.84 (bm, 1H,
THP 2-CH), 5.08 (t, 1H, J = 5.4 Hz, 6-CH), 5.12 (bm, 1H,
22-CH), 5.35 (bm, 1H, 23-CH).
2.7. 24-Methylenecholest-5,6-en-3β-ol (9)
About 42 mg of 80% NaH-paraffin (1.75 mmol of sodium
hydride) mixture was placed in a two-neck flask flushed with
argon. The paraffin was washed away with petroleum ether
(30–60 ◦C) and 5 ml of anhydrous dimethyl sulfoxide was
added into the flask after the sodium hydride had been dried
under reduced pressure under argon. The mixture was stirred
at 80 ◦C for about 40 min under the argon atmosphere, and
a dark green solution was produced. After cooling to room
temperature, a solution of 400 mg (1 mmol) of methyltriph-
enylphosphonium iodide (12) in 4 ml of anhydrous dimethyl
sulfoxide was added to the dark green solution, and the so-
lution turned yellow immediately. After 10 min, a solution
of 50 mg (0.13 mmol) of 8 in 4 ml of anhydrous dimethyl
sulfoxide was added, and the resulting mixture was stirred
at 80 ◦C for 4 h. At the end of this time, the reaction mixture
was cooled, diluted with 15 ml of cold water, and extracted
thoroughly with ether. The combined organic extracts were
washed with water and saturated sodium chloride. After
drying over anhydrous sodium sulfate, the solvent was re-
moved under reduced pressure, and the resulting crude prod-
uct was purified by flash chromatography on silica gel using
petroleum ether (bp 60–90 ◦C)/EtOAc (5:1) as the eluent to
give 43 mg of 9 as white crystals (86%), mp 148–149 ◦C.
IR (KBr) ν: 3416, 3078, 1644, 1461, 1377, 1053, 955, 885,
842, 800 cm−1. 1H NMR (CDCl3, 500 MHz) δ: 0.68 (s, 3H,
18-CH3), 0.95 (d, 3H, J = 6.5 Hz, 21-CH3), 1.01 (s, 3H,
19-CH3), 1.03 (dd, 6H, J = 7.0 and 2.5 Hz, 26-CH3 and
27-CH3), 3.54 (tt, 1H, J = 11.5 and 5.0 Hz, 3-CH), 4.66 (d,
1H, J = 1.5 Hz, 28-CH), 4.71 (d, 1H, J = 1.5 Hz, 28-CH),
5.35 (dd, 1H, J = 3.0 and 2.5 Hz, 6-CH).
2.4. Cholest-5-en-3β-ol-22-al (6)
White solid (62%), mp 142–143 ◦C. IR (KBr) ν: 3409,
3029, 2713, 1721, 1461, 1377, 1060, 955, 842, 800 cm−1
.
1H NMR (CDCl3, 500 MHz) δ: 0.73 (s, 3H, 18-CH3), 1.02
(s, 3H, 19-CH3), 1.13 (d, 3H, J = 6.5 Hz, 21-CH3), 2.37
(m, 1H, 20-CH), 3.53 (tt, 1H, J = 11.5 and 5.0 Hz, 3-CH),
5.35 (dd, 1H, J = 2.5 and 3.5 Hz, 6-CH), 9.58 (d, 1H,
J = 3.5 Hz, 22-CH).
2.5. Cholest-5,22-dien-3β-ol-24-one (7)
The compounds (3-methyl-2-oxobutyl)-triphenylarso-
nium bromide (11) (140 mg; 0.30 mmol), K2CO3 (70 mg;
0.5 mmol) and 0.03 ml of formamide were added to a so-
lution of 6 (73 mg; 0.22 mmol) in 4 ml of MeCN, and the
mixture was stirred at room temperature for 9 h under an
argon atmosphere. Then the suspension was filtered, and
the solid was washed three times with EtOAc. The solvent
was removed under vacuum, and the residue was purified
by flash chromatography on silica gel using petroleum ether
(bp 60–90 ◦C)/EtOAc (4:1) as the eluent. The product was
further purified by recrystallization from MeOH to give
61 mg of 7 (69%), mp 114–116 ◦C. IR (KBr) ν: 3423, 1693,
1665, 1623, 1461, 1053, 990 cm−1
.
1H NMR (CDCl3,
2.8. 24-Methylenecholest-4-en-3,6-dione (10)
500 Hz) δ: 0.73 (s, 3H, 18-CH3), 1.01 (s, 3H, 19-CH3),
1.10 (d, 9H, J = 6.5 Hz, 21-CH3, 26-CH3, 27-CH3), 2.83
(m, 1H, J = 7.0 Hz, 25-CH), 2.21–2.31 (bm, 3H, 7-CH2,
20-CH), 3.53 (m, 1H, 3-CH), 5.35 (dd, 1H, J = 3 and 2 Hz,
6-CH), 6.07 (d, 1H, J = 15.5 Hz, 23-CH), 6.72 (dd, 1H,
J = 15.5 Hz, J = 9 Hz, 22-CH).
Pyridinium chlorochromate (PCC) (240 mg; 1.1 mmol)
was added in one portion to a solution of 9 (70 mg;
0.18 mmol) in dried CH2Cl2 (4 ml). The reaction mixture
was stirred at room temperature for 48 h. Ether (15 ml) was
then added to the mixture, and the suspension was poured