Acid-catalyzed rearrangement of some steroidal isoxazolidines

Abstract

Acid-catalyzed reaction of the steroidal Δ 1 -unsaturated 3β,5β- epoxyimino compound 2 and Δ 3 -unsaturated 1β,5β-epoxyimino products 3 and 7, results in intramolecular rearrangement involving the N-CH 3 group to give the corresponding perhydro-3,1-oxazine derivatives 9-11. Under similar reaction conditions, the saturated analogues 4, 6 and 8 remain unchanged. The difference in reactivity between the unsaturated and saturated compounds is studied and elucidated by the semiempirical molecular orbital MNDO-PM3 method.