1: diphenylamine With sodium hydride in tetrahydrofuran; dimethyl sulfoxide T=0°C; 1 h; 2: carbon disulfide in tetrahydrofuran; dimethyl sulfoxide T=0°C; 0.5 h; 3: chloromalonic acid diethyl ester in tetrahydrofuran; dimethyl sulfoxide T=20°C; 2 h; Cooling;

in tetrahydrofuran; dimethyl sulfoxide T=-20 - 20°C; 2 h;