1: pyrrolidin-1-yl-2,5-dione With lithium diisopropyl amide; tris-(dimethylamino)-phosphine in tetrahydrofuran T=-78°C; 1 h; 2: ethyl iodide in tetrahydrofuran T=-78°C; 0.5 h;

tri-n-butyl-tin hydride; 2,2'-azo-bisisobutyronitrile in ethanol T=80°C; 15 h; Irradiation;

T=190°C;