2,2'-azo-bisisobutyronitrile; triethyl borane; tri-n-butyl-tin hydride 1) toluene, hexane, room temperature, 1.5 h, 2) toluene, hexane, 85 deg C, 1.5 h; Yield givenMultistep reaction;

Lawesson's reagent in toluene 1 h; Heating;

di(n-butyl)tin oxide in 1,4-dioxane Heating;