Studies in the steroid group. Part LXXIX. Preparation of 2-aza-3-oxo, 3-aza-2-oxo-, 16-aza-17-oxo-, and 17-aza-16-oxo-5α-androstane, and of 3-aza-2-oxo-5α-cholestane

Abstract

The steroids named in the title have been prepared by routes in which the yields at all stages are higher than 70%. For the ring-A lactams the key stages involve ring opening of 3-oxa- and 3-aza-2,4-diones; attack by nucleophiles occurs selectively at position 4. 17-Aza-5α-androstan-16-one is readily obtained by Beckmann rearrangement of the 16-hydroxyimino-17-ketone to 17-aza-D-homo-5α-androstane-16,17α-dione, followed by Hofmann degradation. The 16-aza-17-oxo-isomer was prepared from the 17-ketone in six stages by a sequence similar to that used previously for other 16-azasteroids.