Chiral Betti base immobilized on UiO-66-NH2: Synthesis and catalytic application in the asymmetric Henry reaction

Newly developed chiral heterogeneous ligands were prepared by immobilizing chiral ( R )-(−)- and ( S )-(+)-Betti bases onto functionalized UiO-66-NH 2 . Both synthesized chiral homogeneous and heterogeneous ligands were characterized using various techniques, including 1 H NMR, 13 C NMR, FT-IR, XRD, TGA/DTA, SEM, and BET/BJH. The catalytic performance of their copper complexes was evaluated in the asymmetric Henry reaction under solvent-free green conditions, achieving chiral β -nitro alcohols in good yields and moderate enantioselectivity. Reusability studies demonstrated that the catalyst performance was almost maintained during the first two cycles, whereas the third cycle showed a marked decline in catalytic performance.