Efficient and recyclable Cu2(BPDC)2(DABCO)-catalyzed direct amination of activated sp3 C[sbnd]H bonds by N–H heterocycles

Abstract

A metal-organic framework Cu2(BPDC)2(DABCO) was successfully synthesized and employed as an efficient heterogeneous catalyst for the direct CN cross-coupling reaction via sp3 CN bond activation between N–H heterocycles and amides. Kinetic investigation was thoroughly conducted. The optimal conditions involve the use of Cu2(BPDC)2(DABCO) catalyst (3%), di-tert-butyl peroxide oxidant (2 equivalents) in chlorobenzene solvent at 120°C in 2h. The Cu2(BPDC)2(DABCO) offered higher catalytic activity than that of other Cu-MOFs such as Cu2(BPDC)2(BPY), Cu3(BTC)2 and Cu2(BDC)2(DABCO), and that of several common copper salts such as CuCl, CuBr, CuI, Cu(NO3)2, and CuSO4. To investigate the mechanism, catalyst poisoning experiments and reactions with added radical scavengers were conducted. Furthermore, the catalyst could be recovered and reused several times without much decline in the reaction yield.