Regioselective synthesis of pyrroloquinolines - Approaches to Martinelline

Article abstract of DOI:10.1016/S0040-4039(98)02569-6

Indium trichloride catalysed Diels-Alder reaction of imines derived from anilines with cyclic enamides regioselectively gave the biologically important pyrroloquinoline nucleus, with a cis ring junction, in moderate yield. Although the exo:endo selectivity was in most cases poor, these isomers are readily separated by flash chromatography. The functionality tolerated at both C2 and C7 should allow further elaboration to Martinelline.