1: 57 percent / 1.) thiourea, 2.) aq. NaOH / ethanol / Heating; 1.) 44 h 2: iodine, triethylamine / CHCl3 / 3 h View Scheme

1: SOCl2 / CHCl3 / 1 h / Ambient temperature 2: CHCl3 / 0.5 h / Heating 3: 57 percent / 1.) thiourea, 2.) aq. NaOH / ethanol / Heating; 1.) 44 h 4: iodine, triethylamine / CHCl3 / 3 h View Scheme

iodine; triethylamine in chloroform 3 h; Yield given. Yields of byproduct given;