Highly enantioselective alkylation of glycine methyl and ethyl ester derivatives under phase-transfer conditions: its synthetic advantage
摘要:
Phase-transfer alkylation of the benzophenone Schiff base of glycine methyl or ethyl ester (2) was found to be catalyzed by 3,4,5-F-3-C6H2-NAS-Br [(S,S)-1] with high efficiency and excellent enantioselectivity. This procedure allows facile derivatization of the resulting alkylation products to other synthetically useful chiral building blocks. (C) 2003 Elsevier Ltd. All rights reserved.
Stereodivergent Synthesis of Enantioenriched γ‐Butyrolactones Bearing Two Vicinal Stereocenters Enabled by Synergistic Copper and Iridium Catalysis
作者:Lu Xiao、Liang Wei、Chun‐Jiang Wang
DOI:10.1002/anie.202107418
日期:2021.11.15
bearing two vicinal stereocenters are accessible with excellent diastereoselective and enantioselective control. The chiral IrIII -π-allyl intermediate was separated and characterized to understand the origin of the regio- and stereoselectivity of the initial C-Cbondformation process. Control experiments shed some light on the catalyst/substrate and catalyst/catalyst interactions in this dual catalytic
凭借作为双原子合成子的偶氮甲碱叶立德的全新反应模型,我们展示了通过协同 Cu/Ir 催化的不对称级联烯丙基化/内酯化以及 γ 的所有四种立体异构体立体发散制备 γ-丁内酯的第一个例子带有两个邻位立体中心的丁内酯可通过出色的非对映选择性和对映选择性控制获得。手性 IrIII -π-烯丙基中间体被分离和表征,以了解初始 CC 键形成过程的区域选择性和立体选择性的起源。对照实验揭示了这种双催化系统中催化剂/底物和催化剂/催化剂相互作用,以合理化具有不同催化剂组合的相关动力学/动态动力学拆分过程。
Synergistic Cu/Pd‐Catalyzed Asymmetric Allenylic Alkylation of Azomethine Ylides for the Construction of α‐Allene‐Substituted Nonproteinogenic α‐Amino Acids
作者:Hua‐Chao Liu、Yuan‐Zheng Hu、Zuo‐Fei Wang、Hai‐Yan Tao、Chun‐Jiang Wang
DOI:10.1002/chem.201901046
日期:——
This dual catalytic system possesses good substrate compatibility, delivering a diverse array of nonproteinogenic α‐allenylic α‐mono‐ or α,α‐disubstituted α‐aminoacids (α‐AAs) with high yields and generally excellent enantioselectivities. Furthermore, the scalability and practicability of the current synthetic protocol were proven by performing gram‐scale reactions and by the first catalytic asymmetric
Convenient preparation of highly active phase-transfer catalyst for catalytic asymmetric synthesis of α-alkyl- and α,α-dialkyl-α-amino acids: application to the short asymmetric synthesis of BIRT-377
A highly active phase-transfer catalyst was conveniently prepared from the known, easily available (S)-4,5,6,4′,5′,6′-hexamethoxybiphenyldicarboxylic acid. This catalyst exhibited the high catalytic performance (0.01–1 mol %) in the asymmetricalkylation of N-(diphenylmethylene)glycine tert-butyl ester and N-(p-chlorophenylmethylene)alanine tert-butyl ester compared to the existing chiral phase-transfer