New chiraldiphosphinites were prepared starting from (+)-diethyl tartrate. The asymmetrichydrogenation of dehydroamino acids, itaconic acid and dehydrodipeptides was studied using Rh(I)-diphosphinite catalysts. In the hydrogenation of dehydroamino acid derivatives, an introducion of ω-(dimethylamino)alkyl group in the ligands did not raise the optical yield. By the use of Rh(I)-diphosphinite having
Asymmetric Hydrogenation of Dehydrodipeptides with Rhodium(I)–Chiral Diphosphinites. Selective (<i>S</i>,<i>S</i>)- and (<i>R</i>,<i>R</i>)-Product Formation by Double Asymmetric Induction
stereoselectivities, depending on the chiral center of the substrates. This result was ascribed to the electrostaticinteractionbetween the ligand and substrate. POP’s without ω-(dimethylamino)alkyl group gave (R,R)-product for (R)-substrate in a high stereoselectivity by the steric effect between the ligand and substrate, while for (S)-substrate, (S,S)-product was obtained in a low stereoselectivity.
Electrostatic interaction and induced fitting of the rhodium(I) complex coordinated by diphosphine ligand having an amino group in the diastereoselective hydrogenation of dehydrodipeptides
3-propanediyl]bis(diphenylphosphine) (DPP-AE) catalyst achieved an effective 1,4-asymmetricinduction and afforded high diastereoselectivity (max. 96% d.e.) in the hydrogenation of dehydrodipeptides in protic solvents. Activation parameters indicate the important role of the electrostaticinteraction for the asymmetricinduction in the hydrogenation. Structural study of the rhodium(I) DPP-AE complex by 31P NMR and
铑(I)-[2- [2-(2-(二甲基氨基)乙基] -1,3-丙二基]双(二苯基膦)(DPP-AE)催化剂实现了有效的1,4-不对称诱导并提供了高非对映选择性(最大96) %DE)在质子溶剂dehydrodipeptides的氢化。活化参数表明静电相互作用对于氢化中的不对称感应的重要作用。铑(I)DPP-AE配合物的结构研究通过31 P NMR和圆二色性光谱学表明,配合物的诱导拟合是由于配体(DPP-AE)与脱氢二肽之间的静电相互作用而发生的,从而改变了DPP-AE的主要偏构型。根据底物的手性中心的配合物。
Synthesis of chiral dipeptides by means of asymmetric hydrogenation of dehydro dipeptides