Further rearrangements of cyclopropyl epoxides. Formation of cyclobutanes and cyclobutenes

Abstract

Cyclopropyl epoxides having aryl substituents in the 1-position of the cyclopropane ring underwent acid-catalysed rearrangement to 1- and 2- arylcyclobutenes; in methanol they formed stereoisomeric 1-aryl-1-methoxycyclobutanes. A cyclopropyl epoxide substituted in the 2-position of the cyclopropane ring by geminal methyl groups rearranged to a hexa-2,5-dien-1-ol rather than a 3,6-dihydro-2H-pyran. Except in the formation of stereoisomeric pent-2-en-1-ols, cyclopropyl epoxides unsubstituted in the alicyclic ring underwent typical epoxide reactions.