Chiral Proline-Decorated Bifunctional Pd@NH2-UiO-66 Catalysts for Efficient Sequential Suzuki Coupling/Asymmetric Aldol Reactions

The design and development of site-isolating and multifunctional catalysts for multistep sequential reactions at the molecular level is a significant challenge. Herein, we first report bifunctional metal NPs@chiral MOFs catalysts for asymmetric sequential reactions. Pd nanoparticles and chiral proline were successfully added to NH2-UiO-66 to construct two chiral bifunctional catalysts, in which active Pd nanoparticles were encapsulated into the frameworks via the bottle-around-ship method, and chiral proline was introduced into NH2-UiO-66 by coordination to zirconium nodes and postsynthetic modification (PSM) of the organic linkers. The chiral proline-decorated bifunctional Pd@NH2-UiO-66 catalysts were applied to sequential Suzuki coupling/asymmetric aldol reactions with excellent coupling performance (yields up to 99.9%) and good enantioselectivities (ee(anti) values up to 97%). The heterogeneous catalyst by coordination of proline can be reused, and the reaction activity was not significantly reduced after four cycles.