An unprecedented MnI/AgI‐relay‐catalyzed C(sp2)−H/C(sp3)−H coupling of (vinyl)arenes with α‐diazoketones is reported, wherein the diazo group was exploited as a traceless auxiliary for control of regioselectivity. Challenging β‐(hetero)aryl/alkenyl ketones were obtained through this operationally simple approach. The cascade process merges denitrogenation, carbene rearrangement, C−H activation, and
据报道,前所未有的Mn I / Ag I中继催化(乙烯基)芳烃与α-重氮酮的C(sp 2)-H / C(sp 3)-H偶联,其中重氮基被用作无痕助剂控制区域选择性。具有挑战性的β-(杂)芳基/烯基酮是通过这种操作简单的方法获得的。级联过程合并了脱氮,卡宾重排,CH活化和加氢芳基化/加氢烯基化。该方法的鲁棒性已在制备规模上得到证明,并应用于天然产物的后期多样化。
Forming All‐Carbon Quaternary Stereocenters by Organocatalytic Aminomethylation: Concise Access to β
<sup>2,2</sup>
‐Amino Acids
作者:Kai Wang、Jianliang Yu、Ying Shao、Shengbiao Tang、Jiangtao Sun
DOI:10.1002/anie.202009892
日期:2020.12.21
The asymmetric synthesis of β2,2‐amino acids remains a formidable challenge in organic synthesis. Here a novel organocatalytic enantioselective aminomethylation of ketenes with stable and readily available N,O‐acetals is reported, providing β2,2‐amino esters bearing an all‐carbonquaternarystereogenic center in high enantiomeric ratios with a catalytic amount of chiral phosphoric acid. Typically,
Carbenes are highly active reaction intermediates, which can be used as reaction precursors to modify organisms, drugs, and material molecules. In this work, we realized a new cheap metal-catalyzed carbonylation of carbene to give propanedioic acid derivatives. With copper salt as the catalyst, synthetically important malonates and related compounds were produced in good yields under mild reaction
Five ketenes, phenyl(ethyl)ketene, phenyl(methylthio)ketene, diphenylketene, pentafluorophenylketene, and 1-naphthylketene, were generated flash photolytically and solvent isotope effects (H2O vs. D2O) on their hydroxide-ion-catalyzed hydration in aqueous solution were determined. The values obtained are all weakly inverse and closely similar (k(HO)/k(DO) = 0.76-0.97), as expected for these fast, hydroxide-ion-consuming reactions, known to proceed by nucleophilic attack of hydroxide on the ketene carbonyl group. The characteristic magnitude of these isotope effects should prove useful in identifying new examples of this reaction.
Rao, T. S. S.; Pritzkow, W., Journal fur praktische Chemie (Leipzig 1954), 1987, vol. 329, # 4, p. 617 - 625