Excellent enantioselectivities (ee >99%) and good activities (TOF >1200 h−1) are achieved under mild reaction conditions in the Rh-catalyzed hydrogenation of α,β-unsaturated carboxylic acid derivatives with the first family of phosphine–phosphite ligands containing a sugar backbone; these ligands are better than their diphosphine, diphosphite and phosphinite analogues.
A new class of efficient catalysts was developed for the asymmetric hydrogenation of alpha,beta-unsaturated carboxylic acid derivatives by synthesizing a series of novel phosphine-phosphite ligands (4a-d) derived from readily available D-(+)-xylose. Excellent enantioselectivities (> 99%) were achieved under very mild reaction conditions (1 bar H(2) and 20 degrees C). Varying the biphenyl substituents
通过合成一系列衍生自易于获得的D-(+)-木糖的新型膦-亚磷酸酯配体(4a-d),开发了一种新型的高效催化剂,用于α,β-不饱和羧酸衍生物的不对称氢化。在非常温和的反应条件(1 bar H(2)和20摄氏度)下实现了出色的对映选择性(> 99%)。亚磷酸酯部分中联苯取代基的变化极大地影响了氢化反应中的对映选择性。结果还表明对映选择性的感觉主要由亚磷酸酯部分的构型控制。