实现了非天然三肽作为靛红的不对称醛醇缩合反应的高度对映选择性有机催化剂的开发。以d-丙氨酸残基为C末端氨基酸残基的H-Pro-Gly- d -Ala-OH表现出最佳的对映选择性。H-Pro-Gly- d -Ala-OH催化的靛红反应生成的各种羟醛加合物的收率高达93%,ee高达97%。通过DFT计算对过渡态的研究表明,通过d-丙氨酸控制的空间环境实现了高光学纯度。
Natural amino acid salt catalyzed aldol reactions of isatins with ketones: highly enantioselective construction of 3-alkyl-3-hydroxyindolin-2-ones
作者:Gong Chen、Yuan Ju、Tao Yang、Zicheng Li、Wei Ang、Zitai Sang、Jie Liu、Youfu Luo
DOI:10.1016/j.tetasy.2015.07.008
日期:2015.9
The asymmetric synthesis of 3-alkyl-3-hydroxyindolin-2-ones via direct aldolreaction of isatin with ketones catalyzed by natural amino acid salts is described, in which the phenylalanine lithium salt was found to be the best catalyst. This strategy was then applied to a variety of isatin and ketone substrates and the corresponding aldol products were obtained in excellent yields (up to 97%) with good
l-proline-derived bifunctional organocatalyst. This strategy allows the enantioselective synthesis of a variety of 3-alkyl-3-hydroxyindolin-2-ones with a stereogenic quaternary carbon center in excellent yields with good to excellent enantiomeric excess. The method has been applied to the enatioselective synthesis of (S)-convolutamydine A successfully.
Unnatural tripeptide as highly enantioselective organocatalyst for asymmetric aldol reaction of isatins
作者:Kazumasa Kon、Yoshihito Kohari、Miki Murata
DOI:10.1016/j.tetlet.2018.12.049
日期:2019.1
The development of unnatural tripeptides as highly enantioselective organocatalysts for the asymmetricaldolreaction of isatins was achieved. H-Pro-Gly-d-Ala-OH with the d-alanine residue as the C-terminal amino acid residue expressed the best enantioselectivity. The H-Pro-Gly-d-Ala-OH-catalyzed reaction of isatins gave various aldol adducts with up to 93% yield and up to 97% ee. Investigation of the
实现了非天然三肽作为靛红的不对称醛醇缩合反应的高度对映选择性有机催化剂的开发。以d-丙氨酸残基为C末端氨基酸残基的H-Pro-Gly- d -Ala-OH表现出最佳的对映选择性。H-Pro-Gly- d -Ala-OH催化的靛红反应生成的各种羟醛加合物的收率高达93%,ee高达97%。通过DFT计算对过渡态的研究表明,通过d-丙氨酸控制的空间环境实现了高光学纯度。
BINAM-prolinamides are very efficient catalyst for the synthesis of non-protected and N-benzyl isatin derivatives by using an aldol reaction between ketones and isatins under solvent-free conditions. The results in terms of diastereo- and enantioselectivities are good, up to 99% de and 97% ee, and higher to those previously reported in the literature under similar reaction conditions. A high variation of the results is observed depending on the structure of the isatin and the ketone used in the process. While 90% of ee and 97% ee, respectively, is obtained by using (Ra)-BINAM-l-(bis)prolinamide as catalyst in the addition of cyclohexanone and α-methoxyacetone to free isatin, 90% ee is achieved for the reaction between N-benzyl isatin and acetone using N-tosyl BINAM-l-prolinamide as catalyst. This reaction is also carried out using a silica BINAM-l-prolinamide supported catalyst under solvent-free conditions, which can be reused up to five times giving similar results.