Beckmann reactions of steroidal spirocyclic oximes derived from the 16β,23:23,26-diepoxy-22-oxo moiety

The Beckmann rearrangement of the syn and anti isomers of the spirocyclic oxime derived from a 16β,23:23,26-diepoxy-5β-cholestan-22-one was studied. Whereas the anti isomer always follows the Beckmann fragmentation course, the syn isomer, depending on the reaction conditions, follows the normal Beckmann rearrangement course and/or the isomerization to the anti isomer followed by the fragmentation course.