Synthesis of 2-Substituted, 3-Dimethylamino-5,6-methylenedioxyindenes and the Corresponding Indanones

D. T. Witiak, D. R. Williams and S. V. Kakodkar, Vilsmeier-Haack Cyclizations:  Synthesis of 2-Substituted, 3-Dimethylamino-5,6-methylenedioxyindenes and the Corresponding Indanones, J. Org. Chem. 1974, 39, 1242–1247.