Silver-Catalyzed Tandem Cyclization of Sulfur Ylides with Terminal Alkynes: Direct Synthesis of Vinylcyclopropanes

Abstract

A novel silver-catalyzed tandem cyclization reaction of electron-deficient terminal alkynes with two molecules of sulfur ylides has been developed. The reaction provides a simple and highly efficient strategy for the synthesis of diversely functionalized vinylcyclopropanes from easily available acyclic starting materials with good to high diastereoselectivities in a single step. Mechanistic studies indicate a sequential reaction mechanism that involves methyl migration, nucleophilic addition, cyclization, electrocyclic ring-opening, and cyclopropanation. Further applications, including synthesis of vinylcyclopropanes bearing dihydroxyl groups, 3-oxabicyclo[3.1.0]hexanes and biphenyls, demonstrated the immense potential of the tandem cyclization.