A post-synthetically modified metal–organic framework for copper catalyzed denitrative C–N coupling of nitroarenes under heterogeneous conditions

Abstract

Here we report, for the first time, the Ullmann C–N coupling reaction of nitroarenes which is achieved by using a copper containing metal–organic framework (MOF) catalyst under heterogenous conditions. The ready availability of nitroarenes and their low cost have made them ideal replacements for haloarenes as electrophilic coupling partners. Notably, the reaction protocol suppresses the by-product formation in the catalytic reaction. The catalyst has been designed and synthesized by two step post-synthesis functionalization of a MOF, viz. dabco MOF-1 with a –NH₂ functional group (DMOF–NH₂). In the post-synthetic treatment, salicylaldehyde has been used for organic modification first and then copper(II) was successfully incorporated onto the inner surface of the porous material. The hybrid porous solid thus obtained has been employed in the catalytic C–N coupling reaction of nitroarenes with a wide variety of amines under heterogeneous conditions, which displayed very high turnover frequencies (TOF) in catalytic reactions attesting its efficacy towards the N-arylation reaction.