1: 5-bromo-5-tributyl-stannyl-1-trimethyl-silyl-1-pentanone With 2,2'-azo-bisisobutyronitrile; tri-n-butyl-tin hydride in benzene 1 h; Heating; 2: (2,4-dinitro-phenyl)-hydrazine in methanol; benzene Further stages.;

2,2'-azo-bisisobutyronitrile; tri-n-butyl-tin hydride in benzene T=80°C; 2 h;