The synthesis and benzannulation reactions of (trialkylsilyl)vinylketenes

Abstract

(Trialkylsilyl)vinylketenes ("TAS-vinylketenes") are versatile four-carbon building blocks in a variety of methods for the synthesis of carbocyclic and heterocyclic compounds. This thesis discusses the development of a new benzannulation strategy for the synthesis of phenols based on the reaction of TAS-vinylketenes with lithium ynolates. Studies have shown that the reaction proceeds by formation and electrocyclic ring closure of 3-oxidodienylketene intermediates, followed by an intramolecular 1,3-silyl migration to provide highly substituted 3-siloxy phenols. Further transformations of these products providing efficient access to ortho-benzoquinones and benzofuran, benzoxepine, and benzoxocine ring systems are described. Additionally, unsuccessful attempts to prepare TAS-vinylketenes by the rearrangement of siloxy alkynes and by cross-metathesis are discussed.