Pd(ii)-catalyzed domino C–H addition/Heck reaction for stereoselective 3-alkylideneoxindole synthesis

Abstract

3-Alkylideneoxindole derivatives, which constitute the core structural framework of current pharmaceuticals, are widely present as bioactive components in numerous natural molecules. Herein, a Pd-catalyzed cascade synthetic method for the construction of 3-alkylideneoxindoles has been developed, and the reaction sequence comprises aryl C–H activation/intramolecular carbopalladation/Heck cross-coupling. Utilizing 10 mol% Pd(OAc)₂ as the catalyst, 2 equiv. AgOAc as the oxidant, and 1 equiv. Mg(OAc)₂ as the additive, a variety of N-alkyl or N-aryl anilides underwent reaction with alkenes in acetonitrile at 70 °C for 24 h to provide the corresponding (E)-3-alkylideneoxindole products with specific regio- and stereroselectivity in moderate to good yields; the best yield is 64%.