Acid-catalysed ring contraction of steroidal 4β,5β-epoxy-1-en-3-ones
Abstract
The reaction of 17β-acetoxy-4β,5β-epoxy-1-methylandrost-1-en-3-one with formic acid gives rise to a rearrangement, which, involving C(1)–C(10) bond migration, leads to the spirans (2) and (4). The 4β,5β-diol (6), derived from the alternative epoxide cleavage at C-4, is also obtained.