Spin-Center Shift-Enabled Direct Enantioselective α-Benzylation of Aldehydes with Alcohols
作者:Eric D. Nacsa、David W. C. MacMillan
DOI:10.1021/jacs.7b12768
日期:2018.3.7
two-electron pathways. We report herein an enantioselective α-benzylation of aldehydes using alcohols as alkylating agents based on the mechanistic principle of spin-center shift. This strategy harnesses the dual activation modes of photoredox and organocatalysis, engaging the alcohol by SCS and capturing the resulting benzylic radical with a catalytically generated enamine. Mechanistic studies provide
大自然通常使用醇作为离去基团,因为 DNA 生物合成依赖于通过自由基介导的“自旋中心转移”(SCS)机制从核糖核苷二磷酸中去除水。然而,由于醇在双电子途径中的低反应性,醇在合成化学中作为烷化剂仍然没有得到充分利用。我们在此报告了基于自旋中心位移的机械原理,使用醇作为烷化剂的醛的对映选择性 α-苄基化。该策略利用光氧化还原和有机催化的双重激活模式,通过 SCS 与醇结合,并用催化生成的烯胺捕获产生的苄基自由基。机理研究为 SCS 作为关键的基本步骤提供了证据,确定了竞争反应的起源,
[Fe(bpy)<sub>3</sub>]<sup>2+</sup>-based porous organic polymers with boosted photocatalytic activity for recyclable organic transformations
metal porous organic polymers (POPs) based on an iron(II) complex are prepared from the condensation reactions of an octahedral [Fe(bpy)3]2+-cored hexaaldehyde and three rod-like aromatic diamines. The POPs have been studied as the first series of earth-abundant metal complex-connected photocatalysts for heterogeneous visible light-driven oxidation of benzyl halides and enantioselective α-alkylation
Light-Driven Organocatalysis Using Inexpensive, Nontoxic Bi<sub>2</sub>O<sub>3</sub>as the Photocatalyst
作者:Paola Riente、Alba Matas Adams、Josep Albero、Emilio Palomares、Miquel A. Pericàs
DOI:10.1002/anie.201405118
日期:2014.9.1
enantioselective catalytic processes that make use of sunlight as the energy source and nontoxic, affordable materials as catalysts represents one of the new and rapidly evolving areas in chemical research. The direct asymmetric α‐alkylation of aldehydes with α‐bromocarbonyl compounds can be successfully achieved by combining bismuth‐based materials as low‐band‐gap photocatalysts with the second‐generation MacMillan
Visible-Light-Promoted Stereoselective Alkylation by Combining Heterogeneous Photocatalysis with Organocatalysis
作者:Maria Cherevatskaya、Matthias Neumann、Stefan Füldner、Christoph Harlander、Susanne Kümmel、Stephan Dankesreiter、Arno Pfitzner、Kirsten Zeitler、Burkhard König
DOI:10.1002/anie.201108721
日期:2012.4.23
Dream team: Heterogeneous inorganic semiconductors and chiral organocatalysts team up for the stereoselective photocatalytic formation of carbon–carbon bonds. However, the connection between the organic and inorganic catalysts should not be too tight: Covalent immobilization inactivates the system.
Enantioselective Organocatalytic Singly Occupied Molecular Orbital Activation: The Enantioselective α-Enolation of Aldehydes
作者:Hye-Young Jang、Jun-Bae Hong、David W. C. MacMillan
DOI:10.1021/ja0719428
日期:2007.6.6
e products with uniformly high levels of asymmetric induction. Wide latitude in both the aldehyde and enolsilane component is readily accommodated, allowing generic access to a diverse assortment of enantioenriched 1,4-dicarbonyl compounds. This report highlights the potential of SOMO catalysis to enable the development of entirely new classes of asymmetric reactions that have no traditional catalytic