Pyrolysis of 17-oxygenated 16-methylene-20-oxosteroids. Part III. Preparation and pyrolysis of 17α-acetoxy-17β-methyl-16-methylene-17a-oxo-D-homoandrostanes

Abstract

The 17 α-hydroxy-16-methylene steroids (9a), (12), (13), (14), and (16) were converted into the corresponding 17α-acetoxy-17β-methyl-16-methylene-17a-oxo-D-homoandrostanes (10b), (1), (2), (15), and (17), respectively, by treatment with boron trifluoride–ether complex in acetic acid and acetic anhydride. The D-homosteroids (1), (2), and (15) underwent allylic rearrangement to give the corresponding 16-acetoxymethyl-16-dehydro-17-methyl-17a-oxo-D-homoandrostanes (3), (5), and (18), respectively, when pyrolysed at 300°.