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.

Automated summary

Cascade reactions of 1,3-diarylpropane-1,3-dione or unsaturated ketones with arylsulfonyl hydrazide have been achieved via the presence of an iodine source, leading to the synthesis of fully substituted C4-sulfenylated pyrazoles. This method is efficient and practical, utilizing readily available starting materials and providing a useful strategy for constructing different arylthio-substituted pyrazole skeletons.