MCM-41-immobilized bidentate nitrogen copper(I) complex: a highly efficient and recyclable catalyst for Buchwald N-arylation of indoles

The heterogeneous N-arylation reaction of indoles with aryl halides was achieved in toluene at 110 °C by using 4 mol % MCM-41-immobilized bidentate nitrogen copper(I) complex [MCM-41-2N-CuI] as catalyst and K3PO4 as base, yielding a variety of N-arylindoles in good to excellent yields. The heterogeneous copper catalyst exhibited as high activity as homogeneous CuI/diamine catalytic system and can be easily prepared by a simple two-step procedure from commercially available and cheap reagents and recovered by a simple filtration of the reaction solution and reused for 10 cycles with almost consistent activity.

An environmentally friendly, efficient, and practical method for the synthesis of N-arylindoles has been developed by an MCM-41-immobilized bidentate nitrogen copper complex-catalyzed N-arylation reaction of indoles with aryl halides under mild reaction conditions.