Ye Bihai, Su Lei, Zheng Kaiting, Gao Shen, Liu Jiawang
Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai, 201203, China.
Angew Chem Int Ed Engl. 2025 Jan 2;64(1):e202413949. doi: 10.1002/anie.202413949. Epub 2024 Oct 17.
Herein, we report a synergistic photoredox/palladium catalytic system for the efficient enantioconvergent synthesis of axially chiral esters from racemic heterobiaryl (pseudo)halides (bromides/triflates) with CO and alkyl bromides under mild conditions. A wide range of axially chiral esters were obtained in good to high yields with excellent enantioselectivities. Detailed mechanistic studies unveiled that the ratio of photocatalyst and palladium catalyst exhibited significant impact on the chemo- and enantioselectivities of the reaction. Kinetic studies and control experiments supported the proposed mechanism involving cascade asymmetric carboxylation followed by S2 substitution. The achievement of high enantioselectivity relies not only on the choice of synergistic metallaphotoredox catalysts but also on the utilization of alkyl bromides, which trap the generated chiral carboxylic anions in situ, thus preventing their immediate racemization.
在此，我们报道了一种协同光氧化还原/钯催化体系，用于在温和条件下从外消旋杂联芳基（伪）卤化物（溴化物/三氟甲磺酸酯）与一氧化碳和烷基溴高效对映收敛合成轴手性酯。一系列轴手性酯以良好至高收率和优异对映选择性得到。详细的机理研究表明，光催化剂与钯催化剂的比例对反应的化学选择性和对映选择性有显著影响。动力学研究和对照实验支持了所提出的涉及级联不对称羧化随后进行S2取代的机理。高对映选择性的实现不仅依赖于协同金属光氧化还原催化剂的选择，还依赖于烷基溴的使用，烷基溴原位捕获生成的手性羧酸根阴离子，从而防止它们立即消旋化。
