A green method for the synthesis of isoxazolyl aryl thieno[2,3-d]pyrimidinones using reusable polyethylene glycol as simple solvent catalyst and evaluation of anti-microbial activity

Abstract

Novel series of isoxazolyl aryl thieno[2,3-d]pyrimidinones 4 have been synthesized from (E)-2-amino-5-(3-methyl-4-nitroisoxazol-5-yl)-N-(3-methyl-5-styrylisoxazol-4-yl)-4-arylthiophene-3-carboxamide synthon 3. Compound 3 is obtained by reaction of 2-(3-methyl-4-nitro-isoxazol-5-yl)-1-aryl-ethanone 1, N₁-{3-methyl-5-[(E)-2-aryl-1-ethenyl]-4-isoxazolyl}-2-cyanoacetamide 2 and elemental sulfur in PEG-400. Isoxazolyl aryl thieno[2,3-d]pyrimidinones 4 have been obtained from compounds 3 by tandem N-acetylation and cyclodehydration with acetic anhydride. Compounds 3a-q and 4a-q have been characterized by IR, ¹H and ¹³C NMR, and mass spectral data. The title compounds 4a-q have been evaluated for their antimicrobial activity. Compounds 4b, 4c, 4d, 4e, 4j, 4k, 4l and 4m exhibit significant antimicrobial activity, compared to that of standard drugs.