Ligand-free N-arylation of heterocycles using metal-organic framework [Cu(INA)(2)] as an efficient heterogeneous catalyst

摘要

A metal-organic framework [Cu(INA)(2)] was synthesized and used as a heterogeneous catalyst for arylation of a wide range of N-H heterocycles and aryl halides under ligand-free conditions. The N-arylation reaction involved the use of 5 mol% Cu-MOF catalyst with K3PO4 or (BuOLi)-Bu-t as the base in dimethylacetamide (DMA) solvent at 100 degrees C in 6 h. [Cu(INA)(2)] exhibited higher catalytic activity for the N-arylation transformation than that of common homogeneous copper catalysts and other Cu-MOFs with unsaturated open metal sites such as Cu-2(BDC)(2)(BPY), Cu-3(BTC)(2), and Cu-2(BDC)(2)(DABCO). Interestingly, reaction conditions are compatible with a wide range of N-H heterocycles, functional groups, and aryl chlorides. A leaching test indicated no contribution of leached active species in the reaction filtrate. Furthermore, the [Cu(INA)(2)] catalyst could be facilely separated from the reaction mixture and recovered and reused several times without a significant degradation in catalytic activity.