cyclopentanols with three contiguous stereocenters were prepared with impressive diastereocontrol through a samarium diiodide induced 5-exo-trig radical process. The chiral unsaturated oxo ester precursors were prepared with ee values up to 90 % from propionaldehyde through a two-step organocatalyzed aldolization and Wittig–Horner olefination reaction sequence.
通过二碘化钐诱导的 5-exo-trig 自由基过程制备了具有三个连续立体中心的取代环戊醇,并具有令人印象深刻的非对映控制。通过两步有机催化醛醇化和 Wittig-Horner 烯化反应序列,由丙醛制备了 ee 值高达 90% 的手性不饱和羰基合成酯前体。
Diphenylprolinol Methyl Ether: A Highly Enantioselective Catalyst for Michael Addition of Aldehydes to Simple Enones
作者:Yonggui Chi、Samuel H. Gellman
DOI:10.1021/ol0517729
日期:2005.9.1
[reaction: see text] Diphenylprolinol methyl ether catalyzes intermolecular Michaeladdition of simple aldehydes to relatively nonactivated enones with the highest enantioselectivities reported to date (95-99% ee) and significantly lower catalyst loadings than have been typical in this arena.
Direct Enantioselective Michael Addition of Aldehydes to Vinyl Ketones Catalyzed by Chiral Amines
作者:Paolo Melchiorre、Karl Anker Jørgensen
DOI:10.1021/jo026837p
日期:2003.5.1
enantioselectivities, using aldehydes and, e.g., methyl vinyl ketone as starting compounds. Taking into account that the chiral amine can activate the aldehyde and/or the enone, the mechanism for the reaction has been investigated. On the basis of intermediate synthesis, nonlinear effect, and theoretical investigations, the mechanism for the catalytic direct enantioselective Michael addition of aldehydes to vinyl ketones
A General Organocatalyst for Direct α-Functionalization of Aldehydes: Stereoselective C−C, C−N, C−F, C−Br, and C−S Bond-Forming Reactions. Scope and Mechanistic Insights
作者:Johan Franzén、Mauro Marigo、Doris Fielenbach、Tobias C. Wabnitz、Anne Kjærsgaard、Karl Anker Jørgensen
DOI:10.1021/ja056120u
日期:2005.12.1
The development of a general organocatalyst for the alpha-functionalization of aldehydes, via an enamine intermediate, is presented. Based on optically active alpha,alpha-diarylprolinol silyl ethers, the scope and applications of this catalyst for the stereogenic formation of C-C, C-N, C-F, C-Br, and C-S bonds are outlined. The reactions all proceed in good to high yields and with excellent enantioselectivities. Furthermore, we will present mechanistic insight into the reaction course applying nonlinear effect studies, kinetic resolution, and computational investigations leading to an understanding of the properties of the alpha,alpha-diarylprolinol silyl ether catalysts.