Tandem Cyclization and Aromatization of Sulfur Bridged Diallenic Systems: Potential Enediyne Models

Abstract

The synthesis and base catalyzed rearrangement of bis-γ-phenylpropargyl sulfone, sulfoxide and sulfonium salts are described. In contrast to the first two compounds which undergo a fast acetylene to allene isomerization followed by a tandem cyclization and aromatization via a diradical mechanism, the latter compound undergoes a [2,3]-sigmatropic shift via the corresponding ylide intermediate.