Yang Shuang, Che Wen, Wu Hui-Ling, Zhu Shou-Fei, Zhou Qi-Lin
State Key Laboratory and Institute of Elemento-Organic Chemistry , Nankai University , Tianjin 300071 , China . Email:
Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Tianjin 300071 , China.
Chem Sci. 2017 Mar 1;8(3):1977-1980. doi: 10.1039/c6sc03764j. Epub 2016 Nov 15.
We developed neutral iridium catalysts with chiral spiro phosphine-carboxy ligands (SpiroCAP) for asymmetric hydrogenation of unsaturated carboxylic acids. Different from the cationic Crabtree-type catalysts, the iridium catalysts with chiral spiro phosphine-carboxy ligands are neutral and do not require the use of a tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BAr) counterion, which is necessary for stabilizing cationic Crabtree-type catalysts. Another advantage of the neutral iridium catalysts is that they have high stability and have a long lifetime in air. The new iridium catalysts with chiral spiro phosphine-carboxy ligands exhibit unprecedented high enantioselectivity (up to 99.4% ee) in the asymmetric hydrogenations of various unsaturated carboxylic acids, particularly for 3-alkyl-3-methylenepropionic acids, which are challenging substrates for other chiral catalysts.
我们开发了带有手性螺环膦-羧基配体（SpiroCAP）的中性铱催化剂，用于不饱和羧酸的不对称氢化反应。与阳离子型Crabtree类催化剂不同，带有手性螺环膦-羧基配体的铱催化剂呈中性，不需要使用四[3,5-双（三氟甲基）苯基]硼酸盐（BAr）抗衡离子，而该抗衡离子对于稳定阳离子型Crabtree类催化剂是必需的。中性铱催化剂的另一个优点是它们具有高稳定性，并且在空气中具有较长的寿命。新型带有手性螺环膦-羧基配体的铱催化剂在各种不饱和羧酸的不对称氢化反应中表现出前所未有的高对映选择性（高达99.4% ee），特别是对于3-烷基-3-亚甲基丙酸，这是其他手性催化剂难以处理的底物。
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