Synthesis of N-Sulfonyl Pyrazoles Through Cyclization Reactions of Sulfonyl Hydrazines with Enaminones Promoted by p-TSA

A strategy for the rapid synthesis of 3-substituted N-sulfonyl pyrazoles via p-TSA-promoted cyclization reactions of sulfonyl hydrazines with N,N-dimethyl enaminones has been developed. This method achieves both the formation of pyrazole ring and the continued retention of sulfonyl group, providing a series of 3-substituted N-sulfonyl pyrazoles in moderate to good yields with good functional group tolerance, easily available starting materials, and can be scaled-up.