Copper-Catalyzed Synthesis of Substituted 4-Acylpyrazole Derivatives through a Cascade Transformation from N-Propargylic Sulfonylhydrazones and Diaryliodonium Salts

A concise strategy for the synthesis of substituted 4-acylpyrazole derivatives from N-propargylic sulfonylhydrazones and diaryliodonium salts has been developed. The pyrazole derivatives are formed through a five-step cascade sequence that includes intramolecular cyclization, hydroxylation, elimination, copper-catalyzed aerobic oxidation, and intramolecular rearrangement.