Acid-catalysed reactions of 1α,2α-epoxy-1β-methyl- and 1α-hydroxy-1β-methyl-5α-steroids

Abstract

The reaction of 1 a,2a-epoxy-1 P-methyl-5a-androstane-3~,17P-diol diacetate (4) with boron trifluoride-ether leads to both the A-nor derivative (5) and the 2a-hydroxy-1 -methylene compound (6). The epoxide (4) on treatment with acetic anhydride-acetic acid and toluene-p-sulphonic acid gives, depending upon temperature, the 1 af2P-diacetoxy-compound (1 1 ) or the 2p-acetoxy-1 -methylene compound (1 2), while with formic acid gives the 2-formate (1 3) of the 1 a,2P-diol. The reaction of 1 ct,2ct-epoxv-l/3-methyl-5ct-androstane-3a,l7~-diol diacetate ( 14) with boron trifluoride affords the A-noraldehyde (1 5) and the 1 -methylene derivative (1 6). 1 /3-Methyl-5cc-androstane-1 a,3/3,17P-triol 3,17-diacetate (1 9) with toluene-p-sulphonic acid is simply acetylated to give (20) and dehydrated to give (21 ).