Solid acid-catalyzed one-pot multi-step cascade reaction: Multicomponent synthesis of indol-3-yl acetates and indol-3-yl acetamides in water

Abstract

A solid acid-catalyzed cascade reaction of condensation/intermolecular nucleophilic addition/intramolecular cyclization, esterification and amination has been developed to rapidly construct complex polysubstituted indole compounds. This one-pot, three-step five-component cascade reaction affords a series of 2-(4-oxo-1,2-diphenyl-4,5,6,7-tetrahydro-1H-indol-3-yl) acetamide derivatives with good yield under mild conditions. The present procedure exhibited some attractive features, including inexpensive and easy available reagents, large substrate scope, separable intermediate products, recyclable solid acid catalyst, and more importantly, it can be conveniently performed by simple one-pot three-step procedure, involving the sequential mixture of 3-(arylamino)cyclohex-2-en-1-ones, 2,2-dihydroxy-1-arylethan-1-ones, meldrum acid, and alcohols, anilines in the of solid acid at 80 °C. Significantly, this strategy not only expands the application range of solid acid, but also provides a series of 2-(4-oxo-1,2-diphenyl-4,5,6,7-tetrahydro-1H-indol-3-yl)acetate/acetamide derivatives.