Site-Selective C−S Bond Formation at C−Br over C−OTf and C−Cl Enabled by an Air-Stable, Easily Recoverable, and Recyclable Palladium(I) Catalyst

Abstract

This report widens the repertoire of emerging PdI catalysis to carbon–heteroatom, that is, C−S bond formation. While Pd0-catalyzed protocols may suffer from the formation of poisonous sulfide-bound off-cycle intermediates and lack of selectivity, the mechanistically diverse PdI catalysis concept circumvents these challenges and allows for C−S bond formation (S–aryl and S–alkyl) of a wide range of aryl halides. Site-selective thiolations of C−Br sites in the presence of C−Cl and C−OTf were achieved in a general and a priori predictable fashion. Computational, spectroscopic, X-ray, and reactivity data support dinuclear PdI catalysis to be operative. Contrary to air-sensitive Pd0, the active PdI species was easily recovered in the open atmosphere and subjected to multiple rounds of recycling.