上海交通大学崔勇团队报道了用于催化不对称氢化反应的二膦基共价有机框架中单膦-金属配合物的构建。相关研究成果于2023年3月10日发表于国际一流学术期刊《美国化学会杂志》。

螯合许多过渡金属以形成稳定螯合络合物的优秀二膦配体在各种催化过程中是必不可少的。然而，催化活性部分的确切身份仍不明确，因为螯合金属催化剂可能在催化过程中发生重排，生成单膦-金属络合物，这很难分离和评估活性。

通过利用两个磷原子的分离，研究人员在共价有机框架（COFs）中成功构建手性单膦–二膦配体的Ir/Ru配合物，用于对映选择性氢化。通过对映体MeO-BIPHEP的四醛与线性芳族二胺的缩合，研究人员制备了两个具有ABC堆叠的同手性二维COFs，其中每个二膦的两个P原子被分离并固定得很远。因此，与均相螯合类似物相比，COFs的合成后金属化提供了单中心Ir/Ru–单磷酸催化剂，其在喹啉和β-酮酯的不对称氢化中表现出优异的催化和可回收性能，提供高达99.9%的对映体过剩。由于多孔催化剂能够吸附和浓缩氢，催化反应在环境/中压下进行，对于均相催化，通常在高压下进行。

该项工作不仅表明二膦的单膦-金属络合物可以作为不对称氢化反应的催化活性中心，而且为制备新型特权膦基多相催化剂提供了新的策略。

附：英文原文

Title: Construction of Monophosphine–Metal Complexes in Privileged Diphosphine-Based Covalent Organic Frameworks for Catalytic Asymmetric Hydrogenation

Author: Zehao Zheng, Chen Yuan, Meng Sun, Jinqiao Dong, Yan Liu, Yong Cui

Issue&Volume: March 10, 2023

Abstract: Privileged diphosphine ligands that chelate many transition metals to form stable chelation complexes are essential in a variety of catalytic processes. However, the exact identity of the catalytically active moieties remains ambiguous because the chelated metal catalysts may undergo rearrangement during catalysis to produce monophosphine–metal complexes, which are hard to isolate and evaluate the activities. By taking advantage of the isolation of two phosphorus atoms, we demonstrate here the successful construction of chiral monophosphine–Ir/Ru complexes of diphosphine ligands in covalent organic frameworks (COFs) for enantioselective hydrogenation. By condensation of the tetraaldehyde of enantiopure MeO-BIPHEP and linear aromatic diamines, we prepare two homochiral two-dimensional COFs with ABC stacking, in which the two P atoms of each diphosphine are separated and fixed far apart. Post-synthetic metalations of the COFs thus afford the single-site Ir/Ru–monophosphine catalysts, in contrast to the homogeneous chelated analogues, that demonstrated excellent catalytic and recyclable performance in the asymmetric hydrogenation of quinolines and β-ketoesters, affording up to 99.9% enantiomeric excess. Owing to the fact that the porous catalyst is capable of adsorbing and concentrating hydrogen, the catalytic reactions are promoted under ambient/medium pressure, which are typically performed under high pressure for homogeneous catalysis. This work not only shows that monophosphine–metal complexes of diphosphines can be catalytically active centers for asymmetric hydrogenation reactions but also provides a new strategy to prepare new types of privileged phosphine-based heterogeneous catalysts.

DOI: 10.1021/jacs.2c11037

Source: https://pubs.acs.org/doi/10.1021/jacs.2c11037