A Practical Method for Enantioselective Synthesis of All-Carbon Quaternary Stereogenic Centers through NHC-Cu-Catalyzed Conjugate Additions of Alkyl- and Arylzinc Reagents to β-Substituted Cyclic Enones
作者:Kang-sang Lee、M. Kevin Brown、Alexander W. Hird、Amir H. Hoveyda
DOI:10.1021/ja062061o
日期:2006.6.1
Cu-catalyzed enantioselectiveconjugateadditions of alkyl- and arylzinc reagents to unactivated cyclic beta-substituted enones. Transformations are promoted in the presence of 2.5-15 mol % of a readily available chiral NHC-based Cu complex, affording the desired products bearing all-carbon quaternary stereogenic centers in 67-->98% yield and in up to 97% ee. Catalytic enantioselective reactions can
我们展示了 Cu 催化的烷基和芳基锌试剂对未活化的环状 β 取代烯酮的对映选择性共轭加成的第一个例子。在 2.5-15 mol% 的易于获得的基于手性 NHC 的 Cu 络合物的存在下促进了转化,以 67->98% 的产率和高达 97% 的 ee 提供了带有全碳四元立体中心的所需产品。催化对映选择性反应可以在台式上进行,使用未蒸馏的溶剂和市售(未进一步纯化)的铜盐。提供了机械模型,说明了对映选择性的观察水平和趋势。
Formation of Quaternary Centers by Copper-Catalyzed Asymmetric Conjugate Addition of Alkylzirconium Reagents
作者:Mireia Sidera、Philippe M. C. Roth、Rebecca M. Maksymowicz、Stephen P. Fletcher
DOI:10.1002/anie.201303202
日期:2013.7.29
Pure and simple: Alkylzirconocenes generated in situ from simple alkenes are used in highly enantioselective copper‐catalyzed 1,4‐addition reactions to trisubstituted cyclic enones to generate quaternarycenters. These reactions operate at room temperature under a range of conditions and tolerate many functional groups. Cp=cyclopentadienyl, Tf=trifluoromethanesulfonyl.
The copper-catalyzedasymmetricconjugateaddition of Grignard reagents to trisubstituted cyclic enones affords enantioenriched all-carbon quaternarycenters with up to 96% ee. The chiral ligand is a diaminocarbene, directly generated in situ. The combination of Grignard reagent and diaminocarbene is unprecedented in conjugateaddition, and the additon of the phenyl group, on such enones, cannot be
Formation of Quaternary Chiral Centers by N-Heterocyclic Carbene-Cu-Catalyzed Asymmetric Conjugate Addition Reactions with Grignard Reagents on Trisubstituted Cyclic Enones
The copper‐catalyzedconjugateaddition of Grignard reagents to 3‐substituted cyclic enones allows the formation of all‐carbon chiral quaternary centers. We demonstrate in this article that N‐heterocyclic carbenes act as efficient chiral ligands for this transformation. High enantioselectivities (up to 96 % ee) could be obtained for a variety of substrates.
Copper-Catalyzed Asymmetric Conjugate Addition with Chiral SimplePhos Ligands
作者:Laëtitia Palais、Alexandre Alexakis
DOI:10.1002/chem.200901577
日期:2009.10.12
they can be highly functionalised. Herein we report the copper‐catalysed asymmetricconjugateaddition of diethyl zinc and trialkylaluminium reagents with SimplePhos ligands, which gives high enantioselectivity with cyclic enones, acyclic enones and nitro‐olefins, with up to 98.6 % ee. Of particular interest is the reaction of trialkylaluminium reagents with a wide range of 3‐substituted enones, thus