反应详情

温度

80 °C

A mixture of 3β-Acetoxy-17-chloro-16-formylandrosta-5,16-diene (2, 2.5 g, 6.65 mmol), benzimidazole (2.35 g, 19.9 mmol), and K2CO3 (2.76 g, 23.9 mmol) in dry DMF (20 mL) is stirred at ca. 80° C. under Ar for 1.5 h. After cooling to room temperature, the reaction mixture is poured onto ice-cold water (250 mL) and the resulting precipitate is filtered, washed with water, and dried to give a crude dirty white solid (ca. 2.9 g). Purification by FCC [petroleum ether/EtOAc/Et3N (6:4:0.3)] gives 2.7 g (88.7%) of pure compound 3: mp 227-230° C.; IR (CHCl3) 3691, 3024, 2951, 2359, 1725, 1670, 1604, 1491, 1452, 1375, 1253, 1032, 897, 852, 818, 700, 657, 618, 576, 565, 550, 529, 511, 476 cm−1; 1H NMR (300 MHz, CDCl3) δ 1.07 (s, 6H, 18- and 19-CH3), 2.04 (s, 3H, 3β-OCH3), 4.60 (m, 1H, 3α-H), 5.43 (br s, 1H, 6-H), 7.35 (br. s, 2H, aromatic-Hs), 7.85 (s, 1H, aromatic-H), 7.98 (s, 1H, aromatic-H), 7.98 (s, 1H-21-H) and 9.59 (s, 1H, 16-CHO). HRMS calcd 481.2462 (C29H34O3N2.Na+). found 481.2454.

1. temperatureAfter cooling to room temperature
2. additionthe reaction mixture is poured onto ice-cold water (250 mL)
3. filtrationthe resulting precipitate is filtered
4. washwashed with water
5. customdried
6. customto give a crude dirty white solid (ca. 2.9 g)
7. customPurification by FCC [petroleum ether/EtOAc/Et3N (6:4:0.3)]