Palladium-catalyzed endocyclic bond cleavage of thioxanthene-derived sulfonium salts

Abstract

The breaking of the endocyclic S-aryl bond of strainless thioxanthene derivatives by transition metal-catalyzed ring-opening reactions is still underdeveloped. Herein, we present the synthesis of asymmetric triarylmethanes through desymmetric ring-opening reactions of strainless thioxanthene sulfonium salts with palladium catalysis. The reaction exhibited a broad substrate scope, high efficiency, and excellent chemoselectivity. Gram-scale experiments and an asymmetric attempt for enantioselective and endocyclic bond-breaking reactions of the six-membered diarylthiolium salts were also investigated. Meanwhile, compound 3p showed comparatively good inhibition activities on NO generation in RAW264.7 cells through anti-inflammatory examination.