Two Thiophene-Functionalized Co-MOFs as Green Heterogeneous Catalysts for the Biginelli Reaction.

Two Co(II) metal-organic frameworks (Co-MOFs), namely, [Co(DMTDC)(bimb)] () and {[Co(DPTDC)(bimb)(HO)]·2DMF} () (HDMTDC = 3,4-dimethylthieno[2,3-]thiophene-2,5-dicarboxylic acid, HDPTDC = 3,4-diphenylthieno[2,3-]thiophene-2,5-dicarboxylic acid, bimb = 1,4-bis((1-imidazol-1-yl)methyl)benzene), were obtained by the reaction of flexible N-containing ligand bimb and two structurally related thiophene-containing ligands HDMTDC and HDPTDC, respectively. These Co-MOFs displayed a 3D framework and porous structure, respectively. and the activated sample 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)-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.