Construction of Sulfur-substituted Methylenecyclobutanes via Thioaromatization of [1.1.1]Propellane with Sulfenamides †

Abstract

Herein, we report a metal-free catalytic strategy for the efficient synthesis of sulfur-substituted methylenecyclobutanes through the thioaromatization of [1.1.1]propellane. This unprecedented transformation proceeds with excellent atom economy, broad functional group tolerance, and good scalability. The resulting products contain multiple reactive sites, enabling diverse downstream derivatizations and undersocroing their synthetic utility. Mechaistic studies supported by DFT calculations reveal that the reaction is initiated by the formation of a unique sulfur ylide intermediate, followed by a [2,3]-Wittig rearrangement, an Alder-type reaction involving thioxanthone (TXT), and a final deamination step that delivers the target product and regenerates the catalyst.