Photocycloaddition of benzophenone to α‐angelicalactone and thermal rearrangement of the product

Abstract

Abstractα‐Angelicalactone dissolved in thiophene in the presence of benzophenone was irradiated with uv light in order to find out if the unsaturated lactone behaves either as an olefin capable of yielding a [2 + 2] adduct with the heterocycle or if it rather reacts as a substrate for the excited benzophenone. The isolation of two isomeric oxetanes indicates that the latter is the preferred reaction pathway. One of the oxetanes undergoes an interesting thermal rearrangement.