Intramolecular Rearrangements of But-3-enoic Esters

Abstract

Support for the proposal by Khalafy and Prager¹ of a cheletropic rearrangement of a 6-methylidenecyclohexa-2,4-diene-1-carboxylate under flash vacuum pyrolysis (f.v.p.) conditions has been obtained by a study of the f.v.p. products obtained from methyl 1-methyl-6-methylidenecyclohexa-2,4-diene-1-carboxylate and methyl 2,2-dimethylbut-3-enoate. A significant product in each case arises from a reaction involving decarbonylation and transfer of a methoxy group to C 4 (but-3-enoate numbering).