Catalyst-free, one pot and three-component synthesis of 4′-phenyl-1′H-spiro[indoline-3,2′-quinazolin]-2-ones and 2,4-diphenyl-1,2-dihydroquinazolines

Abstract

A simple, green, efficient and three-component procedure has been developed for the synthesis of 4′-phenyl-1′H-spiro[indoline-3,2′-quinazolin]-2-ones (4a–m and 6a–g) and 2,4-diphenyl-1,2-dihydroquinazolines (8a–l) by the reaction of 2-aminobenzophenones, isatins or aromatic benzaldehydes and ammonium acetate in excellent yields under catalyst-free conditions using ethanol as a solvent. This method provides several advantages such as operational simplicity, higher yields, shorter reaction time and catalyst-free conditions with ethanol as a solvent makes the method eco-friendly as well as economical. All the 4′-phenyl-1′H-spiro[indoline-3,2′-quinazolin]-2-ones were tested for antimicrobial activity against both Gram-positive and Gram-negative bacterial strains including a fungal strain Candida albicans MTCC 3017. Among these, the compounds 4f, 6a, 6c and 6g showed appreciable antibacterial activity with MIC values 7.8μg/ml selectively against Gram-positive bacteria, Micrococcus luteus MTCC 2470. On the other hand, compounds 4j, 4m, 6c and 6g showed good activity with MIC values ranging between 3.9 and 7.8μg/ml against Gram-negative bacteria, Klebsiella planticola MTCC 530.