Enantioselective Synthesis of Quaternary Stereocenters via a Catalytic Asymmetric Stetter Reaction
作者:Mark S. Kerr、Tomislav Rovis
DOI:10.1021/ja047644h
日期:2004.7.1
A new electron-deficient chiraltriazoliumsalt has been shown to catalyze the formation of quaternary stereocenters by an asymmetric intramolecular Stetter reaction. Pentafluorophenyl substitution on an aminoindanol-derived catalyst affords tertiary ether, thioether, and quaternary stereocenters in typically greater than 90% ee and very good chemical yield. Aromatic and aliphatic aldehydes are equally
一种新的缺电子手性三唑盐已被证明可通过不对称分子内 Stetter 反应催化四元立体中心的形成。氨基茚满醇衍生的催化剂上的五氟苯基取代提供了通常大于 90% ee 的叔醚、硫醚和季立体中心和非常好的化学产率。芳香醛和脂肪醛同样是该反应的有效底物。该反应在室温下温和条件下进行,以提供具有其他方法特别难以获得的官能团关系的四元立体中心。
Enantioselective Alkylations of Tributyltin Enolates Catalyzed by Cr(salen)Cl: Access to Enantiomerically Enriched All-Carbon Quaternary Centers
作者:Abigail G. Doyle、Eric N. Jacobsen
DOI:10.1021/ja043601p
日期:2005.1.1
The catalytic asymmetric alpha-alkylation of tributyltinenolates with a range of primary alkyl halides is catalyzed by a chiral Cr(salen) complex. The reaction constitutes the first transition-metal-catalyzed system for alpha-alkylation of carbonyl substrates with this important class of electrophiles, providing access to five-, six-, and seven-membered ring ketone products bearing alpha-quaternary
Addition of 2-nitropropene to the chiral imine derived from 2-methylcyclopentanone and (S)-1-phenylethylamine furnished the expected Michael adduct. The latter compound was then efficiently converted into (R)-pentalenone through a Nef reaction. Condensation of the enamino ester derived from 2-carbethoxycyclopentanone and (S)-1-phenylethylamine with 1-nitropropene gave with excellent diastereo- and enantioselectivity the corresponding Michael adduct. (C) 1999 Elsevier Science Ltd. All rights reserved.