Diaryl sulfoxides from aryl benzyl sulfoxides: A single palladium-catalyzed triple relay process

Abstract

A novel approach to produce diaryl sulfoxides from aryl benzyl sulfoxides is reported. Optimization of the reaction conditions was performed using high-throughput experimentation techniques. The [Pd(dba)2]/NiXantPhos catalyst system successfully promotes a triple relay process involving sulfoxide α-arylation, C-S bond cleavage, and C-S bond formation. The byproduct benzophenone is formed by an additional palladium-catalyzed process. It is noteworthy that palladium-catalyzed benzylative C-S bond cleavage of sulfoxides is unprecedented. A wide range of aryl benzyl sulfoxides, as well as alkyl benzyl sulfoxides with various (hetero)aryl bromides were employed in the triple relay process in good to excellent yields (85-99 %). Moreover, aryl methyl sulfoxides, dibenzyl sulfoxides, and dimethylsulfoxide could be utilized to generate diaryl sulfoxides involving multiple catalytic cycles by a single catalyst. Three for one: The [Pd(dba)2]/NiXantPhos (dba=dibenzylideneacetone) catalyst system successfully promotes a triple relay process involving sulfoxide α-arylation, C-S bond cleavage, and C-S bond formation to give diaryl sulfoxides (see picture). Aryl benzyl sulfoxides, as well as alkyl benzyl sulfoxides reacted with various (hetero)aryl bromides. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.