A. Kost, N. Y. Lebedenko, L. A. Sviridova
Apr 1, 1978
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Journal
Chemistry of Heterocyclic Compounds
Abstract
It is known that 1-arylthiosemicarbazides are cyclized to 2-aminobenzothiazoles in acidic media. This reaction was extended to 1,3- and 1,4-disubstituted thiosemicarbazides. It is shown that the rearrangement proceeds through a step involving the formation of o-aminophenylisothioureas. The reaction conditions and substituents in the benzene ring or attached to the nitrogen atoms of the thiosemicarbazides do not have a substantial effect on the ratio of the resulting 2-amino- and 2-phenyl(methyl)aminobenzothiazoles (1∶1). In the case of m-chlorophenylthiosemicarbazide, 5- and 7-chloro-2-aminobenzothiazoles are obtained in equimolar amounts, whereas the 7 isomer (5∶2) is the major product from m-tolylthiosemicarbazide.