Towards applications of metal–organic frameworks in catalysis: C–H direct activation of benzoxazole with aryl boronic acids using Ni2(BDC)2(DABCO) as an efficient heterogeneous catalyst?

Catalysis Science & Technology Pub Date: 2013-10-15 DOI: 10.1039/C3CY00503H

Abstract

A crystalline porous metal–organic framework Ni2(BDC)2(DABCO) was synthesized and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), atomic absorption spectrophotometry (AAS), and nitrogen physisorption measurements. The Ni2(BDC)2(DABCO) could be used as an efficient heterogeneous catalyst for the nickel-catalyzed direct heterocycle C–H arylation reactions between azoles and arylboronic acids forming 2-arylbenzoxazoles as the principal product. This approach avoids the use of hazardous aryl halides as well as the formation of halide byproducts in the synthesis of aryl-substituted benzoxazoles. The Ni2(BDC)2(DABCO) exhibited significantly higher catalytic activity than that of other Ni-MOFs such as Ni3(BTC)2, Ni(HBTC)(BPY), and that of some common nickel salts such as NiCl2, Ni(NO3)2, Ni2SO4, and Ni(OAc)2. To the best of our knowledge, application of Ni2(BDC)2(DABCO) in the field of catalysis as well as the C–C cross coupling reaction via direct C–H functionalization using a nickel heterogeneous catalyst have not previously been reported in the literature.

Graphical abstract: Towards applications of metal–organic frameworks in catalysis: C–H direct activation of benzoxazole with aryl boronic acids using Ni2(BDC)2(DABCO) as an efficient heterogeneous catalyst
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