We describe a column based flow system in which a cinchona alkaloid based reagent/catalyst solid-phase promotes the asymmetric a-chlorination of acid chlorides to afford highly optically active alpha-chloroesters in high enantiomeric excess and in good yields. (c) 2005 Published by Elsevier Ltd.
Generation of Ketenes from Acid Chlorides Using NaH/Crown Ether Shuttle-Deprotonation for Use in Asymmetric Catalysis
作者:Andrew E. Taggi、Harald Wack、Ahmed M. Hafez、Stefan France、Thomas Lectka
DOI:10.1021/ol0172525
日期:2002.2.1
[GRAPHICS]We describe methodology for the in situ generation of reactive monosubstituted ketenes from acid chlorides through a shuttle deprotonation process using NaH as an inexpensive stoichiometric base and a crown ether cocatalyst. We have successfully applied this new procedure to the catalytic, asymmetric synthesis of beta-lactams and alpha-haloesters.
Catalytic, Asymmetric α-Chlorination of Acid Halides
作者:Stefan France、Harald Wack、Andrew E. Taggi、Ahmed M. Hafez、Ty R. Wagerle、Meha H. Shah、Crystal L. Dusich、Thomas Lectka
DOI:10.1021/ja039046t
日期:2004.4.1
process that produces highly optically enriched α-chloroesters from inexpensive, commercially available acidhalides using cinchona alkaloid derivatives as catalysts and polychlorinated quinones as halogenating agents. We have performed kinetics and control experiments to investigate the reaction mechanism and establish conditions under which the reactions can be best performed. We have developed NaH and
我们全面介绍了串联催化、不对称氯化/酯化过程,该过程使用金鸡纳生物碱衍生物作为催化剂和多氯醌作为卤化剂,从廉价的市售酰卤中生产高度光学富集的 α-氯酯。我们已经进行了动力学和控制实验,以研究反应机理并建立可以最好地进行反应的条件。我们开发了 NaH 和 NaHCO3 穿梭基系统作为进行反应的最简单和最具成本效益的方法,使该方法与已知的手性卤化程序在经济上具有竞争力。我们还通过将产品转化为合成有用的衍生物来证明我们的反应的效用。