Tetrabutylammonium Iodide Mediated Sulfenylation of Poly­substituted 1H-Pyrazol-5-amines with Arylsulfonyl Hydrazides

Abstract A TBAI-mediated sulfenylation of N ,3-diaryl-1-arylsulfonyl-1 H -pyrazol-5-amines with arylsulfonyl hydrazides has been established, and an expanded inventory of N ,5-diaryl-4-(arylthio)-1 H -pyrazol-3-amines was constructed through C–S bond formation and N–S bond breaking. Mechanistic investigations suggest thiosulfonate as a key intermediate in the sulfenylation, and the detosylation is promoted by the generated arylsulfinic acid. The method is characterized by simple operating conditions, broad substrate range as well as gram-scale reaction.