generated hydroxy‐o‐quinodimethanes with high stereoselectivity. We used a chiral organic catalyst, derived from natural cinchona alkaloids, to activate maleimides toward highly stereoselective Diels–Alder reactions. An unconventional mechanism of stereocontrol is operative, wherein the organocatalyst is actively involved in both the photochemical pathway, by leveraging the formation of the reactive photoenol
Light-Driven Enantioselective Organocatalytic β-Benzylation of Enals
作者:Luca Dell'Amico、Victor M. Fernández-Alvarez、Feliu Maseras、Paolo Melchiorre
DOI:10.1002/anie.201612159
日期:2017.3.13
A photochemical organocatalytic strategy for the direct enantioselective β‐benzylation of α,β‐unsaturated aldehydes is reported. The chemistry capitalizes upon the light‐triggered enolization of 2‐alkyl‐benzophenones to afford hydroxy‐o‐quinodinomethanes. These fleeting intermediates are stereoselectively intercepted by chiral iminium ions, transiently formed upon condensation of a secondary amine
A light-driven, catalyst- and additive-free photoenolization/nucleophilic addition reaction for the synthesis of 3-benzyl-3-hydroxyindolin-2-ones is presented. In this reaction, 2-methylbenzophenones undergo light-induced enolization process to afford hydroxy-o-quinodimethanes (hydroxy-o-QDMs), which are then immediately captured by the electrophilic isatins. The reaction utilizes green and clean light
catalysts with a PNP type ligand, the electron-rich chiral PNP ligands have still been rarely reported because of the difficulties in synthesis and the nature of air-sensitivity. Herein, we report a novel chiral PNP ligand (Heng-PNP) with both a rigid backbone and a bulky tert-butyl group on the phospholane motif. We successfully obtained its divalent iron complex. The chiral environment of its Ir(III) complex
A nontransmetalation reaction pathway for anionic four-electron donor-based palladacycle-catalyzed addition reactions of arylborons with aldehydes
作者:Yuan-Xi Liao、Chun-Hui Xing、Matthew Israel、Qiao-Sheng Hu
DOI:10.1016/j.tetlet.2011.04.074
日期:2011.6
nontransmetalation reaction pathway for anionic four-electron donor-based (Type I) palladacycle-catalyzed additionreactions of arylborons with aldehydes is described. This newreaction pathway offers new catalysis opportunities for Type I palladacycle-catalyzed additionreactions such as the exceptionally low catalyst loading catalysis, with the catalyst loading as low as 0.0005 mol %. This new pathway may