Synthesis of indole-fused 4-pyridone-3-carboxylic acids

Abstract

Some indole-fused tri-and tetracyclic 4-oxo-pyridine-3-carboxylic acids, quinolone-type derivatives, (3), (4), and (5) have been prepared. The synthesis is characterized by the construction of the pyridone ring through the intrarmolecular nucleophilic displacement cyclization at the 2-position of 3-substituted 1-methoxyindole accompanied with demethoxylation.