反应详情

The hydroxy dienone from (a) (0.6 gms) was converted to its trimethylsilyl ether by treatment of a solution in tetrahydrofuran (2 mls) and pyridine (2 mls) with hexamethyldisilazane (1.5 mls) and trimethylchlorosilane (0.6 mls). The crude trimethylsilyl ether was dissolved in tetrahydrofuran (10 mls) and the solution added dropwise to a stirred solution of lithium metal (approx. 200 mgs) in liquid ammonia (20 mls). After a few minutes ammonium chloride (2 gms) was added and the solution stirred. A further portion of lithium metal (approx. 100 mgs) was added. Again the solution was stirred. An additional portion of ammonium chloride was then added and the mixture poured into cold water. The produce was isolated by extraction into ether and methylene dichloride followed by column chromatography which afforded the title compound crystallized from ethanol, melting point 158°-161°. After recrystallisation the melting point was 161.5°-163°. [α]D (CHCl3)-38 °. This material was identical to the product of Example 1(c), and on hydrogenation gave a sample of 1α,3β-dihydroxy-5α-cholestane identical in every way to an authentic specimen.

1. stirringAgain the solution was stirred