A General Redox-Neutral Platform for Radical Cross-Coupling

Sulfonyl hydrazides are disclosed as versatile radical precursors as exemplified with seven new C–C bond forming, redox neutral cross-couplings with: (1) unsaturated olefins, (2) alkyl halides, (3) redox active esters, (4) aryl halides, (5) alkenyl halides, (6) alkynyl halides, and (7) a trifluoromethylating reagent to forge C(sp3)-C(sp3), C(sp3)-C(sp2), and C(sp3)-C(sp) bonds. Sulfonyl hydrazides are stable and usually crystalline substances that can be accessed in a variety of ways including transiently from hydrazones to achieve a net reductive arylation of carbonyl compounds. Exogenous redox (chemical, photo/electrochemical) additives are not necessary as these functional groups serve the dual role of radical precursor and electron donor. The operational simplicity (homogeneous, water tolerant, dump-and-stir) and practicality of the method are demonstrated as well as applications to streamlining synthesis and mild late-stage functionalization.