Two Thiophene-Functionalized Co-MOFs as Green Heterogeneous Catalysts for the Biginelli Reaction
Nana Liu, Jun Zheng, Tingting Liu, Hui Yan, Mengna Ji, Guang‐Ning Liu, Yun‐Wu Li, Jianmin Dou, Fei Yang, Suna Wang
Abstract
Two Co(II) metal–organic frameworks (Co-MOFs), namely, [Co(DMTDC)(bimb)] n ( Co-MOF-1 ) and {[Co(DPTDC)(bimb)(H 2 O)]·2DMF} n ( Co-MOF-2 ) (H 2 DMTDC = 3,4-dimethylthieno[2,3- b ]thiophene-2,5-dicarboxylic acid, H 2 DPTDC = 3,4-diphenylthieno[2,3- b ]thiophene-2,5-dicarboxylic acid, bimb = 1,4-bis((1 H -imidazol-1-yl)methyl)benzene), were obtained by the reaction of flexible N-containing ligand bimb and two structurally related thiophene-containing ligands H 2 DMTDC and H 2 DPTDC, respectively. These Co-MOFs displayed a 3D framework and porous structure, respectively. Co-MOF-1 and the activated sample Co-MOF-2′ could act as green heterogeneous catalysts for the one-pot multicomponent Biginelli reaction, specifically the dehydration condensation process involving aldehydes, acetoacetates, and urea to yield dihydropyrimidin-2(1 H )-ones. The reaction has advantages such as solvent-free conditions, water as only byproduct, readily accessible starting materials, excellent functional group compatibility, and simple operation. Both catalysts exhibited a wide substrate scope and maintained significant catalytic activity over five cycles. The special catalytic performance may be ascribed to functional groups within the ligand.