Rhodium-Catalyzed Asymmetric Hydrogenation of Functionalized Olefins Using Monodentate Spiro Phosphoramidite Ligands
作者:Yu Fu、Xun-Xiang Guo、Shou-Fei Zhu、Ai-Guo Hu、Jian-Hua Xie、Qi-Lin Zhou
DOI:10.1021/jo049655z
日期:2004.7.1
Novel chiral monodentate phosphorus ligands, SIPHOS, were conveniently synthesized from 1,1‘-spirobiindane-7,7‘-diol. The Rh complexes of SIPHOS can catalyze the hydrogenation of α-dehydroamino esters in mild conditions, providing α-amino acid derivatives in up to 99% ee. Enamides and β-dehydroamino esters can also be hydrogenated in good to excellent enantioselectivities (up to 99% and 94% ee, respectively)
新型手性单齿磷配体SIPHOS是由1,1'-spirbibiindane-7,7'-diol方便地合成的。SIPHOS中Rh复合物可以催化的氢化α在温和的条件-dehydroamino酯,提供α在高达99%ee的β-氨基酸衍生物。酰胺和β-脱氢氨基酯也可以以良好至优异的对映选择性(分别高达99%和94%ee)氢化。在N原子上具有较小烷基的SIPHOS配体具有较高的对映选择性。单晶的X射线分析表明,Rh / SIPHOS催化剂的结构为[Rh(COD)((S)-SIPHOS-Me)2 ] +,阐明了在Rh催化的不对称加氢反应中单齿手性磷配体的催化剂构型。在脱氢氨基酸衍生物的氢化中,观察到配体和产物的光学纯度之间的正非线性效应。氢化动力学研究表明,该反应在底物浓度上为零级,在Rh催化剂浓度和加氢压力下为一级。当Rh / L比从1:1变为1:4时,氢化速率降低。