Facile three-component domino reactions in the regioselective synthesis and antimycobacterial evaluation of novel indolizines and pyrrolo[2,1-a]isoquinolines

The domino reactions of pyridine/isoquinoline, bromoacetonitrile/ethyl bromoacetate and a series of beta-nitrostyrenes in the presence of triethylamine afforded novel tri-/disubstituted indolizines and pyrrolo [2,1-a]isoquinolines regioselectively, presumably via substitution-dipole generation-1,3-dipolar cycloaddition-elimination and/or aromatisation sequence. In vitro screening of all the seventeen compounds synthesized against Mycobacterium tuberculosis H37Rv discloses that ethyl 2-(4-fluorophenyl)pyrrolo [2,1-a]isoquinoline-3-carboxylate displays maximum potency with minimum inhibitory concentration (MIC) of 1.0 mu M, being 7.6 and 4.7 times more potent than the standard first line TB drugs, ethambutol and ciprofloxacin, respectively. (C) 2010 Elsevier Ltd. All rights reserved.