An efficient synthesis of 4-pyrano quinolinone derivatives catalysed by a versatile organocatalyst tetra--butylammonium fluoride and their pharmacological screening.

A new series of indole-based pyranoquinoline derivatives has been synthesized by a one-pot cyclocondensation reaction of 2-(4-substituted)phenyl--allyl-indole-3-carbaldehydes ; active methylenes ; and 4-hydroxy-1-substituted quinolin-2(1)-one catalysed by an organocatalyst tetra--butylammonium fluoride (TBAF) in aqueous ethanol. The easy experimental procedure of the reaction leads to excellent yields of pyranoquinoline derivatives. All the compounds were screened against a representative panel of bacteria and fungi. Some of the compounds are found to be equipotent or more potent than standard drugs as evident from the structural activity relationship study.