An efficient one-pot synthesis of carbazole fused benzoquinolines and pyridocarbazoles

Abstract

A one-pot, solvent-free protocol for the synthesis of chloro-substituted benzoquinoline-carbazole derivatives via a modified Friedländer hetero-annulation reaction between 2, 3, 4, 9-tetrahydrocarbazol-1-one and 3-amino-2-naphthoic acid in the presence of POCl 3 is described. In addition, the direct pseudo multicomponent transformation of 2, 3, 4, 9-tetrahydrocarbazol-1-one, malononitrile and 9-ethyl-3-carbazolecarboxaldehyde results in the formation of a multifunctionalized carbazole through a Knoevenagel–Michael addition-cyclization reaction has also been reported. All the newly synthesized molecules were deduced by spectral and analytical methods. Graphical Abstract: A modified Friedländer hetero-annulation reaction between 2, 3, 4, 9-tetrahydro-1H-carbazol-1-one and 3-amino-2-naphthoic acid under solvent-free condition afforded chloro-substituted benzoquinoline-carbazole derivatives. In addition, the direct pseudo multicomponent transformation of 2, 3, 4, 9-tetrahydro-1H-carbazol-1-one, malononitrile and 9-ethyl-3-carbazolecarboxaldehyde results in the formation of dimerised carbazoles.</p