Catalytic  diazosulfonylation of enynals toward diazoindenes via oxidative  radical-triggered 5-exo-trig carbocyclizations

          Wen-Juan Hao, Yan Du, Dan Wang,  Bo Jiang*, Qian Gao, Shu-Jiang  Tu*, Guigen Li*

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

Org. Lett.  2016, 18, 1884-1887