反应详情

3α-Hydroxy-5α-pregnane-11,20-dione (1 g.) in stirred methanol (7 ml.) at 30° was treated with acetyl chloride (1 drop). After two minutes bromine (0.19 ml.) in methanol (4.5 ml.) was added dropwise. The solution being allowed to decolourise between the addition of each drop. The resulting clear solution was poured into chloroform (100 ml.), washed with water (3 × 50 ml.) dried (Na2SO4) and evaporated to a white froth (1.40 g.). Preparative t.l.c. afforded title compound (715 mg.) which crystallised from chloroform/ether as clusters of colourless needles, m.p. 160°-163°; [α]D + 109° (c 0.82).

1. additionto decolourise between the addition of each drop
2. washwashed with water (3 × 50 ml.)
3. dry with materialdried (Na2SO4)
4. customevaporated to a white froth (1.40 g.)