sodium cyanoborohydride; acetic acid T=20°C;

1: With selenenyl bromide resin; tin(IV) chloride in dichloromethane T=-20°C; 0.5 h; 2: With 2,2'-azo-bisisobutyronitrile; tri-n-butyl-tin hydride in toluene T=90°C; 2 h;

1.1: dimethylformamide / 2 h / 20 °C 2.1: ZnCl2 / xylene / 5.5 h / 145 °C 3.1: selenenyl bromide resin; SnCl4 / CH2Cl2 / 0.5 h / -20 °C 3.2: n-Bu3SnH; AIBN / toluene / 2 h / 90 °C View Scheme