Electronic Supplementary Information AuCl 3 catalyzed [3+2+1] cycloaddition: First use of aldehyde as a carbon monoxide-like one carbon synthon for triple C-C coupling Krishnanka S. Gayen and Dilip K. Maiti* Department of Chemistry, University College of Science, University of Calcutta, 92, A. P. C. Road, Kolkata-700009, India e-mail: dkmchem@caluniv.ac.in Contents Page No. 1. Materials and Methods S1 2. General Procedure for Synthesis of Benzopyrano[4,3-c]pyridines and Benzopyrano[4,3-b]pyrroles S1 3. Characterization Data of Benzopyrano[4,3-c]pyridines and Benzopyrano[4,3-b]pyrrole (4a-o,4t and 5a) S2 4. Synthesis and Characterization of Benzofurano[3,2-c]pyridine (9) S10 5. NMR ( 1 H and 13 C) Spectra of All New Synthesized Compounds (4a-o, 4t, 5a and 9) S12 6. Crystal Summary of Data of the Compound 4m (CCDC 938786) S29 Electronic Supplementary Material (ESI) for RSC Advances This journal is © The Royal Society of Chemistry 2013