AuPd Alloys and Chiral Proline Dual-Functionalized NH2-UiO-66 Catalysts for Tandem Oxidation/Asymmetric Aldol Reactions

Rational design and precise engineering of a multifunctional catalyst at the molecular level to fulfill a multi-step tandem procedure still face serious challenges. Here, we first constructed two metal alloy NPs@chiral MOFs bifunctional catalysts, in which stable NH2-UiO-66 was selected as parent MOF, chiral proline was introduced via coordination to the zirconium nodes and tiny AuPd alloy NPs with the Au/Pd ratios of 3:1 and 1:3 were encapsulated into the parent MOF via “bottle-around-ship” method. The bifunctional and heterogeneous catalysts displayed excellent oxidation performance (yield up to 93%) and satisfied enantioselectivities (eeanti value up to 91%) in tandem selective oxidation of aromatic alcohol/asymmetric Aldol reactions. Control experiments showed that there was synergistic effect existed in AuPd NPs, and Au and Pd NPs played a leading and co-catalyst role, respectively, during the oxidation reactions. Macro-substrate experiment suggested that the catalytic reaction occurred inside the pores of the catalysts. The catalysts can also be recycled for at least three times without obvious activity loss and structural change.Graphical AbstractAlloy NPs@chiral MOFs bifunctional catalysts were first constructed, in which stable NH2-UiO-66 was selected as parent MOF, and versatile chiral proline and tiny AuPd alloy NPs were introduced as catalytic sites. They were applied to tandem oxidation/asymmetric Aldol reactions with excellent oxidation performance and satisfied enantioselectivities.