THE ASYMMETRIC HYDROGENATION OF THE α-<i>N</i>-ACETYLAMINOCINNAMOYL DERIVATIVE OF AMINO ACIDS WITH CHIRAL BISPHOSPHINE–RHODIUM COMPLEX
作者:Ken-ichi Onuma、Tomiyasu Ito、Asao Nakamura
DOI:10.1246/cl.1980.481
日期:1980.5.5
An optical yield of the dipeptide obtained in the title reaction is affected by a chiral amino acid moiety in the substrate.
在标题反应中获得的二肽的光学产率受底物中手性氨基酸部分的影响。
Copper‐Catalyzed Direct Perfluoroalkylation of Heteroarenes
作者:Hajar Baguia、Gwilherm Evano
DOI:10.1002/chem.202103599
日期:2022.1.27
An efficient process for the copper-catalyzeddirect perfluoroalkylation of C−H bonds in heteroarenes with commercially available perfluoroalkyl iodides is reported in this work. This reaction is based on a simple combination of copper(I) iodide and phenanthroline enabling the easy reduction of perfluoroalkyl iodides to the corresponding radical species that add to a wide range of heteroarenes. High
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.
A study of the effets of solvent and temperature on the stereoselectivity of asymmetric hydrogenation of dehydrodipeptides has been made with Rh(I)–(DPP-AE) catalyst, in which an electrostatic interaction is possible between the dimethylamino group of the ligand and the carboxyl group of the substrate. The highest stereoselectivity was attained in the MeOH–water solvent, while aprotic solvents such
使用 Rh(I)-(DPP-AE) 催化剂研究了溶剂和温度对脱氢二肽不对称氢化立体选择性的影响,其中配体的二甲氨基与羧基之间可能发生静电相互作用。基体组。在甲醇-水溶剂中获得了最高的立体选择性,而非质子溶剂如 DMF 和 THF 的选择性和反应性相对较低。在醇溶剂中,随着温度从 -40 °C 增加到 80 °C,立体选择性增加,在 20-40 °C 时达到最大值,然后下降。讨论了溶剂和温度对立体选择性的影响。