One pot synthesis and reactions of novel 5-amino[1,3]thiazolo[3,2-b][1,2,4]triazoles

Abstract

5-Mercapto-3-phenyl-1,2,4-triazole 8 was reacted with a variety of cyano compounds containing active methylene group such as ethyl cyanoacetate, cyanoacetamide and malonitrile in boiling acetic acid in the presence of concentrated sulfuric acid, to give the corresponding 5-amino-2phenyl [1,3]thiazolo[3,2-b][1,2,4]triazole-6-carboxylate 10a. While on using cyanoacetamide or malonitrile the 5-amino-2-phenyl[1,3]thiazolo[3,2-b][1,2,4]triazole-6-carboxamide 10b was obtained in one step reaction. Reaction of 10b with triethyl orthoformate, acetic anhydride, benzaldehyde, benzoyl chloride and/or carbon disulfide gave the corresponding 2phenyl[1,2,4]triazolo[2',3':3,2][1,3]thiazolo[4,5-d]pyrimidinones 15-18 in good yield. Upon treatment of 5-mercapto-3-phenyl-1,2,4-triazole 8 with chloroacetonitrile and benzaldehyde in boiling acidified acetic acid afforded 6-benzylidene-2-phenyl[1,3]thiazolo[3,2-b][1,2,4]triazol-5(6H)-one 19 rather than the isomeric product 6-benzylidene-3-phenyl[1,3]thiazolo [2,3c][1,2,4]triazol-5(6H)-one 20 in one pot reaction. The mechanism of the reactions is under investigation and the structures of all new compounds were elucidated using IR, 1 H-NMR, 13 C-NMR, mass spectral data and elemental analysis. The biological activity of selected compounds was investigated and summarized.