An evaluation study of various palladium supports led to the selection of charcoal as the most efficient system for the preparation of oxindoles by sequential Heck-reduction-cyclization (HRC) reactions. The in situ prepared Pd0/C was not recyclable for further cross-coupling reactions but remains still highly active for reduction processes. The sustainable chemistry described herein allows extremely simple experimental protocol Under mild conditions, free of any base, ligand and additive. (C) 2009 Elsevier Ltd. All rights reserved.
Synthesis of Oxindoles by Tandem Heck-Reduction-Cyclization (HRC) from a Single Bifunctional, in Situ Generated Pd/C Catalyst
A tandem sequence involving palladium-catalyzed sequential Heck-reduction-cyclization transformations in mild conditions has been developed for the synthesis of oxindoles. The protocol involves inexpensive reagents and does not require any additives such as base or ligands.