反应详情

A solution of 3α-hydroxy-2β-bromo-5α-pregnan-20-one (8.5 g.) in pyridine (25 ml.) was treated with acetic anhydride (12.5 ml.), and the mixture was allowed to stand at room temperature overnight. The reaction mixture was poured into water and the product was extracted with methylene chloride. The extract was washed with water, dried (Na2SO4) and evaporated. A portion (582 mg.) of the residue (8.5 g.) was purified by preparative t.l.c. and crystallisation from iso-propyl ether to give 3α-acetoxy-2β-bromo-5α-pregnan-20-one (70 mg.), 142°-146°, [α]D + 120.9°.

1. extractionthe product was extracted with methylene chloride
2. washThe extract was washed with water
3. dry with materialdried (Na2SO4)
4. customevaporated
5. customA portion (582 mg.) of the residue (8.5 g.) was purified by preparative t.l.c
6. customand crystallisation from iso-propyl ether