Synthesis of novel 2-amino-4-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-4H-pyran-3-carbonitrile derivatives as antimicrobial and antioxidant agents

As a part of systematic investigation of synthesis and biological activities of indole analogues linked to various heterocyclic systems, we have synthesized new compounds viz., 2-amino-4-(5'-substituted 2'-phenyl-1H-indol-3'-yl)-6-aryl-4H-pyran-3-carbonitriles (2a-i), 4,5-diamino-6-(5'-substituted 2'-phenyl-1H-indol-3'-yl)-8-aryl-2-oxo-2,6-dihydrodipyrano [2,3-b:3,2-e]pyridine-3-carbonitriles (3a-i), 4-amino-5-(5'-substituted 2'-phenyl-1H-indol-3-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-ones (4a-i), 4-amino-5-(5'-substituted 2'-phenyl-1H-indol-3'-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-thiones (5a-i), 4-(5'-subtituted 2'-phenyl-1H-indol-3'-yl)-6-aryl-1,4-dihydropyrano[2,3-c]pyrazol-3-amines (6a-i) and 5-(5'-substituted 2'-phenyl-1H-indol-3'-yl)-7-aryl-3H-pyrano[2,3-d]pyrimidin-4(5H)-ones (7a-i). Antibacterial activity results revealed that, compound 6a showed promising activity versus Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. Compound 6d exhibited good activity against S. aureus, K. pneumoniae and P. aeruginosa. Antifungal activity results indicated that, compound 4d exhibited maximum zone of inhibition against Aspergillus oryzae and Aspergillus flavus. In case of antioxidant activity, compound 4a showed promising radical scavenging activity, ferric ions (Fe+3) reducing antioxidant power (FRAP) and metal chelating activity. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.