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Synthesis 2010(15): 2636-2642  
DOI: 10.1055/s-0030-1258153
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Novel Method for the Synthesis of s-Triazolo[3,4-b][1,3,4]thiadiazines

Hassan A. H. El-Sherief*, Zeniab A. Hozien, Ahmed F. M. El-Mahdy, Abdelwareth A. O. Sarhan
Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt
Fax: +20(88)2342708; e-Mail: dr_Hassanahmed@yahoo.com;
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Publication History

Received 15 March 2010
Publication Date:
07 July 2010 (online)

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Abstract

The reaction of 4-amino-3-mercapto-5-phenyl-s-triazole with aromatic or aliphatic ketones containing active α-hydrogens as a methyl or methylene group using an acidified acetic acid method afforded the corresponding s-triazolo[3,4-b][1,3,4]thiadiazines. In a similar way, applying the same reaction with cyclic ketones afforded the corresponding tricyclic compounds. Interaction of 4-amino-3-mercapto-5-phenyl-s-triazole with chloroacetonitrile under the same reaction conditions directly gave the cyclized 6-amino-s-triazolo[3,4-b][1,3,4]thiadiazine derivative. On treatment of 4-amino-3-mercapto-5-phenyl-s-triazole with acetonitrile or ethyl cyanoacetate under the same reaction conditions, an s-triazolo[3,4-b][1,3,4]thiadiazole derivative was obtained; the reaction carried out with malononitrile or cyanoacetamide gave an alternative s-triazolo[3,4-b][1,3,4]thiadiazole derivative. The mechanism of the reactions was investigated and the structures of all new compounds were elucidated using IR, ¹H NMR, ¹³C NMR and mass spectroscopic data, and elemental analyses.

Key words

α-hydrogens - ketones - nitriles - one-pot reaction - triazolothiadiazines