D-homo-steroids. Part III. The preparation of D-homoandrostane derivatives: a study of the reactions of steroidal C(17)-spiro-oxirans and their derivatives

Abstract

The reaction of epoxides with azide ions, to give hydroxy-azides, proceeds smoothly in dimethylformamide containing boric acid. The resulting azides are conveniently reduced by zinc dust or chromium(II) ions in acidic media to give amine salts. Application of these reactions to the C(17)-spiro-oxirans (VI) afforded the hydroxy-amines (III), converted by nitrous acid into the D-homo-ketones (IV) and (V) in very high overall yield. The preparations of ‘D-homodehydroepiandrosterone’(IVa) and D-homo-5α-androstan-7-one (XVIIb) are described in detail. Other reactions of the C(17)-spiro-oxiran (VIa) were studied, including the addition of hydrogen halides, acid-catalysed rearrangement, and the reaction with guanidine, which gives an imino-oxazolidine derivative (XXIII). Sodamide, ammonia, and some carboxylic amides and imides, did not react usefully with the C(17)-spiro-oxiran. Benzylamine gave the 17-benzylaminomethyl derivative (XX), but this could not be reduced to the aminomethyl compound (III).