(S)-Mandelate-Mediated Dynamic Kinetic Resolution of α-Bromo Esters for Asymmetric Syntheses of Aminoflavones, Dihydroquinoxalinones and Dihydrobenzoxazinones
作者:Yong Sun Park、Yoon Min Lee
DOI:10.3987/com-09-11700
日期:——
(S)-Mandelate-mediated dynamickineticresolution of α-bromoesters in nucleophilicsubstitution reaction has been investigated. Reactions of various aryl amine nucleophiles in the presence of TBAI and DIEA can provide the substitution products 2 and 7-19 up to 95% yield and 96:4 dr. Also, the simple procedure with spontaneous removal of the chiral auxiliary provides a practical protocol for asymmetric
A catalytic amount of Hantzschester that could be regenerated in situ by Ru complexes under hydrogen gas has been employed in the biomimetic asymmetric hydrogenation of benzoxazinones with up to 99% ee in the presence of chiral phosphoric acid. The use of hydrogen gas as a reductant for the regeneration of Hantzschesters makes this hydrogenation an ideal atom economic process.
催化量的 Hantzsch 酯可以在氢气下通过 Ru 络合物原位再生,用于在手性磷酸存在下对苯并恶嗪酮进行仿生不对称氢化,其中 ee 高达 99%。使用氢气作为还原剂来再生 Hantzsch 酯使这种氢化成为一种理想的原子经济过程。
Regenerable Dihydrophenanthridine via Borane-Catalyzed Hydrogenation for the Asymmetric Transfer Hydrogenation of Benzoxazinones
作者:Bochao Gao、Wei Meng、Xiangqing Feng、Haifeng Du
DOI:10.1021/acs.orglett.2c01314
日期:2022.6.10
The highly enantioselective transfer hydrogenation of benzoxazinones with chiral phosphoric acids under H2 was successfully achieved, where boranes promoted the hydrogenation of phenanthridine for the regeneration of dihydrophenanthridine as the hydrogen donor. A variety of dihydrobenzoxazinones were obtained in high yields with up to 99% ee. The current work provides a promising solution to unreactive
成功实现了苯并恶嗪酮与手性磷酸在H 2下的高对映选择性转移加氢,其中硼烷促进菲啶的加氢以再生作为氢供体的二氢菲啶。以高达 99% ee 的高产率获得了多种二氢苯并恶嗪酮。目前的工作为受挫的路易斯对催化的不对称氢化提供了一种有前途的解决方案。
Manganese Pentacarbonyl Bromide as Regeneration Catalyst Enabled Biomimetic Asymmetric Reduction
Using readily available manganese pentacarbonyl bromide as a regeneration catalyst, biomimeticasymmetric reduction of imines including quinoxalinones, benzoxazinones, and benzoxazine has been successfully developed in the presence of transfer catalyst chiral phosphoric acids, providing the chiral amines with high yields and enantioselectivities.
L-Tartaric Acid as a New Chiral Auxiliary for Asymmetric Synthesis of Piperazinones, Morpholinones, Dihydroquinoxalinones and Dihydrobenzoxazinones
作者:Yelim Kim、Kon Ji Park、Yong Sun Park
DOI:10.5012/bkcs.2012.33.11.3853
日期:2012.11.20
2012, Accepted August 10, 2012Key Words : Dynamic resolution, Nucleophilic substitution, Tartaricacid, Chiralauxiliary, Asymmetric syn-thesisDynamic resolution of α-haloacyl compounds in nucleo-philic substitution has been recently developed as an asym-metric synthetic method for α-substituted carboxylic acids.