sulfuric acid T=80 - 85°C; 22 h;

2,2'-azo-bisisobutyronitrile; tri-n-butyl-tin hydride in benzene Inert atmosphereReflux;

1: sodium tetrahydroborate / benzene / 3.5 h / 0 - 20 °C / Inert atmosphere 2: 2,2'-azo-bisisobutyronitrile; tri-n-butyl-tin hydride / benzene / Inert atmosphere; Reflux View Scheme

triethylamine; p-toluenesulfonyl chloride in dichloromethane T=0 - 20°C; 24 h; Inert atmosphere;