我们报告了一种单一的添加剂响应型铬催化系统,用于选择性生产两种不同的内部烯烃异构体中的任何一种。在 HBpin/LiO t Bu 存在下,铬催化剂能够使烯烃在多个碳原子上异构化,得到热力学最稳定的异构体。同一催化剂无需添加剂即可实现末端烯烃在一个碳原子上的选择性异构化,表现出高效且可控的烯烃转位选择性。
Primary Amine/CSA Ion Pair: A Powerful Catalytic System for the Asymmetric Enamine Catalysis
作者:Chen Liu、Qiang Zhu、Kuo-Wei Huang、Yixin Lu
DOI:10.1021/ol200747x
日期:2011.5.20
A novel ion pair catalyst containing a chiral counteranion can be readily derived by simply mixing cinchona alkaloid-derived diamine with chiral camphorsulfonic acid (CSA). A mixture of 9-amino(9-deoxy)epi-quinine 8 and (−)-CSA was found to be the best catalyst with matching chirality, enabling the direct amination of α-branched aldehydes to proceed in quantitative yields and with nearly perfect enantioselectivities
Proline-catalysed asymmetric amination of α,α-disubstituted aldehydes: synthesis of configurationally stable enantioenriched α-aminoaldehydes
作者:Henning Vogt、Sylvia Vanderheiden、Stefan Bräse
DOI:10.1039/b305465a
日期:——
Proline-catalysed amination of α,α-disubstituted racemic aldehydes with azodicarboxylates proceeds smoothly to give configurationally stable scalemic aldehydes and oxazolidinones in up to 86% ee.
activity among carbonyl compounds leading to various competitive side reactions. Herein we reported an efficient Pd-catalyzed asymmetric intermolecular α-arylation reaction of α-alkyl-α-aryl disubstituted aldehydes with aryl bromides, which provides a rapid access to chiralaldehydes bearing an α-all-carbon quaternary stereocenter in moderate to good yields with good er in most cases. In addition, a pair