[EN] CHIRAL PHOSPHINES FOR PALLADIUM-CATALYZED ASYMMETRIC ALPHA-ARYLATION OF ESTER ENOLATES TO PRODUCE TERTIARY STEREOCENTERS IN HIGH ENANTIOSELECTIVITY [FR] PHOSPHINES CHIRALES POUR L'ALPHA-ARYLATION ASYMÉTRIQUE CATALYSÉE PAR LE PALLADIUM DES ÉNOLATES D'ESTER POUR OBTENIR DES STÉRÉOCENTRES TERTIAIRES À UNE ÉNANTIOSÉLECTIVITÉ ÉLEVÉE
Practical and Robust Method for Regio- and Stereoselective Preparation of (<i>E</i>)-Ketene <i>tert</i>-Butyl TMS Acetals and β-Ketoester-derived <i>tert</i>-Butyl (1<i>Z</i>,3<i>E</i>)-1,3-Bis(TMS)dienol Ethers
We developed an efficient, practical, robust method for the regio- and stereoselective preparation of (E)-ketene trimethylsilyl acetals (KSAs) derived from tert-butyl esters 1. The reaction was performed under convenient reaction conditions; LDA−TMSCl, 0−5 °C, and cyclopentyl methyl ether (CPME) solvent. Two kinds of (Z)- and (E)-KSAs derived from α-oxygen and α-nitrogen-substituted tert-butyl esters
An Enantioselective, Intermolecular α-Arylation of Ester Enolates To Form Tertiary Stereocenters
作者:Zhiyan Huang、Zheng Liu、Jianrong (Steve) Zhou
DOI:10.1021/ja2066829
日期:2011.10.12
asymmetric α-arylation of carbonylcompounds, formation of tertiary centers with high enantioselectivity is a longstanding problem, due to easy enolization of the monoarylation products. Herein, we report such examples using a palladium catalyst supported by a new, (R)-H(8)-BINOL-derived monophosphine. Silyl ketene acetals, together with a weakly basic activator, were used as equivalents of ester anions
在过渡金属催化的羰基化合物的不对称α-芳基化中,由于单芳基化产物容易烯醇化,形成具有高对映选择性的三级中心是一个长期存在的问题。在此,我们报告了使用由新的 (R)-H(8)-BINOL 衍生的单膦支持的钯催化剂的示例。甲硅烷基乙烯酮缩醛与弱碱性活化剂一起用作酯阴离子的等价物,它们与芳基三氟甲磺酸酯以优异的对映体过量 (ee) 顺利反应。该反应的有效性在 92% ee 的 (S)-萘普生的克级合成中得到证明。
Hudrlik,P.F. et al., Synthetic Communications, 1975, vol. 5, p. 359 - 365