Palladium-Catalyzed Cyanation of Aryl Sulfonium Salts

Abstract

A palladium-catalyzed cyanation of aryl dimethylsulfonium salts using cheap, nontoxic, and bench-stable K4[Fe­(CN)6]·3H2O as the cyanating reagent has been developed. The reactions proceeded well under base-free conditions with various sulfonium salts and provided aryl nitrile with yields of up to 92%. Aryl sulfides can be transformed to aryl nitriles directly via a one-pot process, and the protocol is scalable. Density functional theory calculations were performed to investigate the reaction mechanism that involved a catalytic cycle involving oxidative addition, ligand exchange, reductive elimination, and regeneration to yield the product.

Palladium-Catalyzed Hiyama-Type Coupling of Thianthrenium and Phenoxathiinium Salts

“…In addition to aryl thianthrenium salts, the use of aryl phenoxathiinium triflate 5a also delivers 4a with excellent NMR yield (91%), while a much lower reactivity was observed by using dibenzo[ b , d ]thiophenium triflates 5b as the arylation source (Figure A). Interestingly, the aryl dialkyl sulfonium salts are inert in this reaction, probably due to the low reactivity of those sulfonium salts in the oxidative addition step with Pd(0) under very mild conditions (Figure A). Taking the consideration that the substituents on organosilanes often have a dramatic effect on the reactivity for the Hiyama coupling, a variety of commercially available phenyl-substituted organosilanes have been evaluated.…”