A mixture of 34 parts of ethyl 3-[[[(2-nitrophenyl)amino]thioxomethyl]amino]-1-pyrrolidinecarboxylate, 56 parts of iron-powder, 2 parts of ammonium chloride, 160 parts of methanol and 30 parts of water was stirred and acidified with hydrochloric acid. Stirring was continued for 2 hours at reflux temperature. The reaction mixture was filtered over diatomaceous earth and the filtrate was evaporated, yielding 30 parts (97.5%) of ethyl 3-[[[(2-aminophenyl)amino]thioxomethyl]amino]-1-pyrrolidinecarboxylate as a residue (interm. 23).
