Synthesis of Thiadiazole and Azetidinone Derivatives Derived from Triazoles

Abstract

Several chemical classes of heterocycles such as thiazole, triazole, oxazole, 1,3,4-thiadiazole and 2-azetidinone are biological active and have been discovered to have remarkable chemical and geometrical similarties [1-5]. The present paper reports conventional as well as microwave assisted chemical preparation of 1,3,4-thiadiazole and 2-oxoazetidine incorporation with mercapto heterocycles [6-13]. The rapid heating capability of the microwave leads to considerable saving in dissolution time, chemical solvents and environmental pollution [14-16]. The condensation of all the steps have been carried out by both conventional and microwave method to give final products. 4-Methyl-4H-1,2,4-triazole-3-thiol on reaction with ethyl bromoacetate gave 4-methyl-3-(methylthio)-4H-1,2,4-triazole (1), which on reaction with thiosemicarbazide afforded 2-[(4methyl-4H-1,2,4-triazalolyl)thioacetyl]thiosemicarbazide (2). The compound 2 on dehydrative annulation by H2SO4 followed by NH3 afforded, 5-[(4-methyl-4H-1,2,4-triazolyl)thiomethyl]-1,3,4-thiadiazol-2-amine (3) (Scheme-I). The compound 3 on condensation with various aromatic aldehyde afforded N-(2substituted benzylidene)-5-((4-methyl-4H-1,2,4-triazolyl)thiomethyl)-1,3,4-thiadiazol-2-amine (4) which on further reaction with chloroacetyl chloride in presence of Et3N afforded 4-(2-bromophenyl)-3-chloro-N-[5-((4-methyl-4H-1,2,4triazolyl)thiomethyl)-1,3,4-thiadiazolyl]-2-oxo-azetidine (5) (Scheme-II).