反应详情

A solution of 3α-hydroxy-2β-methoxy-5α-pregnane-11,20-dione (2 g.) in methanol (15 ml.) was treated with hydrobromic acid in glacial acetic acid (3 drops). The mixture was stirred at room temperature and bromine (530 mg.) in methanol (1.45 ml.) was added dropwise over a period of 30 minutes. The mixture was stirred for a further 30 minutes and poured into water, stirred, filtered, washed with water and dried. Purification by preparative t.l.c., followed by crystallisation from ethyl acetate and petrol gave title compound (250 mg.) as colourless plates; m.p. 185°-188°; [α]D + 104°.

1. stirringThe mixture was stirred for a further 30 minutes
2. stirringstirred
3. filtrationfiltered
4. washwashed with water
5. customdried
6. customPurification by preparative t.l.c
7. custom, followed by crystallisation from ethyl acetate and petrol