New topological Co2(BDC)2(DABCO) as a highly active heterogeneous catalyst for the amination of oxazoles via oxidative C–H/N–H couplings†
Herein, we report the synthesis, structural characterization, and catalytic properties of a new cobalt-based metal–organic framework, Co2(BDC)2(DABCO) (where BDC = 1,4-benzenedicarboxylate and DABCO = 1,4-diazabicyclo[2.2.2]octane), namely VNU-10 (where VNU = Vietnam National University). Single-crystal X-ray diffraction analysis revealed that VNU-10 crystallizes in the hexagonal space group P6/mmm. The structure of this material is comprised of two-dimensional kgm layers which are interconnected by DABCO pillars to afford an overall three-dimensional porous architecture. VNU-10 exhibited exceptional catalytic activity toward the direct amination of oxazoles via C–H/N–H couplings while a previously reported topological isomer, Co2(BDC)2(DABCO), with the sql topology, displayed poor activity. Leaching tests indicated that homogeneous catalysis via leached active cobalt species is unlikely. Furthermore, the VNU-10 catalyst was facilely isolated from the reaction mixture and reused several times without degradation of the catalytic reactivity.