1-Thiocarbamoylthiosemicarbazide, the synthetic equivalent of thiourea and thiosemicarbazide, reacts with phenylchloropyruvic acid methyl ester exclusively as thiourea (Hantzsch reaction) forming 2-hydrazo-4-methoxycarbonyl-5-phenylthiazole. Diacetylation and reductive fission of this hydrazo compound was carried out, and also oxidation to the corresponding azo compound, readily accomplished with using dimethyl sulfoxide. Authors: V. A. Mamedov, I. Z. Nurkhametova, A. T. Gubaidullin, I. A. Litvinov, and Ya. A. Levin. English Translation in Chemistry of Heterocyclic Compounds , 1999, 35 (11), pp 1357-1363 http://link.springer.com/article/10.1007/BF02252009