DESIGN AND SYNTHESIS OF 1, 2, 4 – TRIAZOLE SUBSTITUTED THIOPHENESAbstract
Highly substituted thiophene derivatives first synthesized by Gewald synthesis in 1965, are important heterocyclic compounds present in numerous biologically active compounds. The synthesis of title compounds was carried out by preparing derivatives of Gewald product. In the present study, a series of 2-aminothiophene derivatives were first prepared by Gewald reaction and further converted into 2-aminothiophene-1, 2, 4-triazole derivatives. Knoevenagel condensation of aryl ketones (1a-1d) with ethylcyanoacetate and subsequent treatment of the α-β-unsaturated nitriles (2) with sulfur and amine resulted in the corresponding 2-aminothiophenes (3a-3d), which were used as a starting material for the synthesis of substituted Gewald products. In the subsequent steps (3a-3d) were converted into carbohydrazides (4a-4d). Substituted carbohydrazides were then converted into potassium aryl carbonyl hydrazine carbodithionate (5a-5d) which were further converted into final compound 2-amino thiophene-1, 2, 4-triazole derivatives (6a-6d). The structures of all the synthesized compounds were confirmed by their spectral data (IR and 1H NMR spectroscopy).
N. Singla*, J. Bariwal and S. Kaur
Department of Pharmaceutical Chemistry, ISF College of Pharmacy, Moga, Punjab, India.
28 April, 2017
14 June, 2017
07 July, 2017
01 January, 2018