Access to Substituted Carbazoles in Water by a One-Pot Sequential Reaction of α,β-Substituted Nitro Olefins with 2-(3-Formyl-1H-indol-2-yl)acetates

Abstract

A series of interesting new multifunctional carbazole scaffolds have been prepared in good to excellent yields by an organocatalytic one-pot two-step sequential reaction between α-alkyl-β-substituted nitro olefins or α-alkyl-δ-substituted nitro-dienes and 2-(3-formyl-1H-indol-2-yl)acetates in water at room temperature followed by treatment with 2 n HCl under mild conditions. This one-pot, organocatalytic, oxidant-free, mild, and eco-friendly process may provide a powerful alternative synthetic protocol to rapidly access 3-alkyl-substituted carbazole frameworks that have a close structural resemblance to biologically active natural carbazoles. Moreover, biologically significant cyclic imide- and quinolinone-fused carbazoles have been efficiently prepared by using this synthetic method. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.