Cu(0)@Al2O3/SiO2 NPs: an efficient reusable catalyst for the cross coupling reactions of aryl chlorides with amines and anilines

Abstract

The C–N cross coupling reaction of aryl chlorides with various alkyl/aryl amines catalyzed by copper nanoparticles impregnated on alumina/silica support (Cu(0)@Al₂O₃/SiO₂) was investigated. The prepared catalyst was characterized for its intrinsic physico-chemical and textural properties using XRD, XPS, HR-TEM, BET surface area, SEM-EDAX, H₂-TPR and ICP-AES techniques. The catalyst exhibits excellent reactivity and efficacy in the cross-coupling of a wide range of alkyl/aryl amines including challenging anilines with aryl chlorides. The catalyst offers significant advantages such as brevity, milder reaction conditions, excellent yields and high functional group tolerance for C–N cross coupling when compared with the other reported methods. Moreover, this atom-economical methodology does not require an additional ligand or co-catalyst/activator. The Cu(0)@Al₂O₃/SiO₂ catalyst was efficiently applied to a gram scale synthesis of 7-chloro-4-(4-(2-nitrophenyl)piperazin-1-yl)quinolone (2k). The robustness of the catalyst was examined by reusing it for five consecutive runs.