Photoredox-catalyzed arylative and aryl sulfonylative radical cascades involving diaryliodonium reagents: synthesis of functionalized pyrazolones.

We disclose a photoredox-catalyzed arylative radical cascade between '-arylidene--acryloylhydrazides and diaryliodonium reagents to obtain the corresponding benzylated pyrazolones in good yields. The protocol was extended to three-component coupling involving the 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) (DABSO) adduct as a sulfur dioxide surrogate for the synthesis of arylsulfonylated pyrazolones. Both reactions exhibit broad scope, scalability, and high functional group tolerance.