已经开发出确定β-手性伯醇的绝对构型的方法。在对映选择性酰化催化剂HBTM的任何一种对映异构体的存在下,将富含对映体的醇酰化,并通过使用1 H NMR光谱分析测量产物转化率来确定更快的反应。开发了经验助记符,其将醇的绝对构型与更快反应的催化剂相关联。该方法成功的底物包括在立体异构中心带有“指导基团”的伯醇。指导基团包括芳烃,杂芳烃,烯酮和卤化物。
Novel AC regioisomer cationic cyclodextrins have been successfully prepared with azide/alkyne click chemistry. The clicked CDs were explored for the enantioseparation of acidic racemates in capillary electrophoresis.
ORD and CD measurements on α-alkylphenylaceticacids with primary, secondary, and tertiary α-substituents agree with the evidence from gas chromatographie retention times of their diastereoisomeric amides in leading to the conclusion that all (+)- acids of the series possess the same configuration.
Highly Enantioselective Direct Alkylation of Arylacetic Acids with Chiral Lithium Amides as Traceless Auxiliaries
作者:Craig E. Stivala、Armen Zakarian
DOI:10.1021/ja205107x
日期:2011.8.10
A direct, highly enantioselective alkylation of arylacetic acids via enediolates using a readily available chiral lithium amide as a stereodirecting reagent has been developed. This approach circumvents the traditional attachment and removal of chiralauxiliaries used currently for this type of transformation. The protocol is operationally simple, and the chiral reagent is readily recoverable.
An effective kinetic resolution of racemic α-arylpropanoic acids, α-arylbutanoic acids, and β-substituted-α-arylpropanoic acids with bis(9-phenanthryl)methanol as a new achiral nucleophile in the asymmetric esterification using carboxylic anhydrides and the acyl-transfer catalyst
kinetic resolution of racemic α-arylalkanoic acids with achiral alcohols is described. It was determined that bis(9-phenanthryl)methanol is a suitable nucleophile which reacts with the intermediary mixed anhydrides generated from aromatic anhydrides with α-arylpropanoic acids or β-substituted-α-arylpropanoic acids in the presence of (+)-benzotetramisole to produce the corresponding opticallyactive esters