Delta-16 20-keto steroids prepn - by monodebrominating a 17-alpha-dibromoacetyl-17-beta-acyloxy steroid and eliminating the ac

摘要

Steroids (I) of partial formula: (where R1 is Me or Et, R2 is H or lower acyl; R3 is the residue of a steroid molecule) are prepd by partially debrominating a steroid of partial formula: with a soln of a reducing metal salt, pref. a Cr2+ or V2+ salt, and heat-treating the 17 alpha-monobromoacetyl-17 beta-acyloxy steroid thus obtd in a polar aprotic solvent in the presence of an alkali(ne earth) metal salt of a lower carboxylic acid to give the DELTA 16-21-acyloxy-20-keto steroid, and opt. removing the 21-acyl gp. The products (I) are intermediates for pharmaceuticals.