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 7.8 μg/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 7.8 μg/ml against Gram-negative bacteria, Klebsiella planticola MTCC 530.