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Paper | Regular issue | Vol 75, No. 4, 2008, pp.847-857
Published online, 11th January, 2008
DOI: 10.3987/COM-07-11268
Synthesis of Nitrogen-Containing Heterocycles 11. 1,2,4-Triazole Formation through Disproportionation of Polyazapolyenes

Yoshiko Miyamoto

*Department of Chemistry, Kitasato University of Japan, 1-15-1 Kitasato, Sagamihara, Kanagawa 228-8555 Japan

Abstract

Aromatic diaminomethylenehydrazones 1-4 were reacted with bis(methylthio)methylenemalononitrile (BMM) to give 5-aryl-1-benzyl-3-dimethylamino-1H-1,2,4-triazoles (5-8) via disproportionation in fused condition in moderate to high yields (44-78 %). Little or no effect was observed on disproportionation products in connection with substituents on the benzene ring. When used an equimolar amount of two different diaminomethylenehydrazones 3 and 4, four types of 5-aryl-1-benzyl-3-dimethylamino-1H-1,2,4-triazoles were obtained. In the reaction using two (different) benzaldehyde S-methylisothiosemicarbazones 22 and 23, four types of 5-aryl-1-benzyl-3- methylthio-1H-1,2,4-triazoles were formed in 14-26 % yield. The structural assignment of products and reaction mechanism are discussed.