Arylazo-steroids. Part IV. The reaction of phenylhydrazine and 1-methyl-1-phenylhydrazine with bromo- and dibromo-5α-cholestanones; osazone formation from α-halogeno-ketones

Abstract

The reaction of phenylhydrazine with 2α-bromo- and 2,2-dibromo-5α-cholestan-3-ones affords initially isolable arylazo-alkenes, followed by the bisphenylhydrazone of 5α-cholestane-2,3-dione. The osazone is thought to arise by a 1,4-addition of arylhydrazine to the arylazo-alkene. Phenylhydrazine and 1 α,2β-dibromo-5α-cholestan-3-one gave the phenylhydrazone of 2-bromo-5α-cholest-1-en-3-one, while from 5α,6β-dibromocholestan-3-one was obtained an arylazo-alkadiene, 3-phenylazocholesta-3,5-diene. These products are thought to arise through the ene-hydrazine form of the intermediate phenylhydrazones. Reaction of 2α-bromo- and 2,2-dibromo-cholestan-3-ones with 1-methyl-1-phenylhydrazine yielded a heterocyclic steroid which probably arose from cyclization of an intermediate osazone.