1: 81 percent / tributyltinhydride, AIBN / benzene / 4 h / Heating 2: 70 percent / 15percent H2SO4 / CH2Cl2 / 20 h / Ambient temperature View Scheme

2,2'-azo-bisisobutyronitrile; tri-n-butyl-tin hydride in benzene 4 h; Heating;