Zr and Hf-metal-organic frameworks: Efficient and recyclable heterogeneous catalysts for the synthesis of 2-arylbenzoxazole via ring open pathway acylation reaction

Zirconium- and hafnium-based metal-organic frameworks which constructed by 12-coordinated clusters and 6-coodinated clusters were shown to be highly effective heterogeneous catalysts for the ring opening acylation of benzoxazole to 2-arylbenzoxazole under solvent free conditions. Owning the wide opening spaces structures and inherent formate sites, MOFs based on 6-connected Zr-6/Hf-6 node were able to identify a significantly enhanced yield in Bronsted acid catalyzed reactions under conventional heating and microwave irradiation. In addition, the detailed mechanism of active sites of the ring opening acylation reaction was confirmed by employing of density functional theory (DFT) calculations. (C) 2019 Elsevier Inc. All rights reserved.