Hydroformylation of 2-Alkynylanilines: Toward an Alternative Methodology for the Synthesis of 3-Substituted Indoles

摘要

A potentially viable route for the synthesis of 3-substituted indoles is presented herein. The methodology is based on a regioselective Rh-catalysed hydroformylation of prepared 2-alkyn-1-ylanilines. The requisite 2-alkynylaniline substrates were prepared in high yields (>85%) using the Pd-catalysed Sonogashira reaction. A catalyst complex that comprises RhI(CO)(PPh3)(3) and 1,2-bis(diphenylphosphino) ethane as the ligand allowed the quantitative conversions of the alkynyl substrates with selectivities >75% for the desired 3-substituted indoles.