The cyclisation of a series of ethyl 3′-aryl-4′, 6′-dimethoxyindol-2′-yl-2-(hydroxyimino) acetates was investigated using 1H NMR spectroscopy to determine the mechanism of formation of the corresponding ethyl 9, 11-dimethoxy indolo [2, 3-c] quinoline-6- carboxylates. The electronic requirements of the reaction were determined and, along with the observation of an intermediate in the process, indicated that the reaction proceeds ...