Iodine‐Promoted Tandem Pyrazole Annulation and C−H Sulfenylation for the Synthesis of C4‐Sulfenylated Pyrazoles

Cascade reactions of 1,3‐diarylpropane‐1,3‐dione or unsaturated ketones with arylsulfonyl hydrazide have been achieved in the presence of iodine source. Fully substituted C4‐sulfenylated pyrazoles were synthesized via the tandem pyrazole annulation and C(sp2)−H sulfenylation. This approach is efficient and practical. The starting materials are readily available, while also providing a useful strategy for the construction of different arylthio‐substituted pyrazole skeletons. Fully substituted C4‐sulfenylated pyrazoles have been synthesized by the tandem pyrazole annulation and C(sp2)−H sulfenylation of 1,3‐dione or unsaturated ketones with arylsulfonyl hydrazide in the presence of iodine source.