Catalytic Diazosulfonylation of Enynals toward Diazoindenes via Oxidative Radical-Triggered 5-exo-trig Carbocyclizations

Catalytic diazosulfonylation of enynals with arylsulfonyl hydrazides has been established by using tert-butyl hydroperoxide (TBHP) as the oxidant with tetrabutylammonium iodide (TBAI) under a convenient system. The reaction occurred through oxidative radical-triggered 5-exo-trig carbocyclization cascading to afford sulfonylated diazoindenes regioselectively. The new diazosulfonylation reaction features a broad substrate scope, readily accessible starting materials, and a simple one-pot process.