2,2'-azo-bisisobutyronitrile; tributyltin chloride; sodium cyanoborohydride; (18)O2 in tert-butyl alcohol T=60°C; 15 h; Yields of byproduct given;

2,2'-azo-bisisobutyronitrile; oxygen; (C4H9)2(tert-C4H9)SnCl; sodium cyanoborohydride in tert-butyl alcohol T=60°C; 10 h; Yields of byproduct given;