high yields within 5–10 min. However, for nitro-substituted derivatives, unexpectedly, N,N-diethylamides were isolated without anhydride formation. These results indicated the pronounced effect of substituents in governing these potential side reactions which can significantly affect the yields of acylation reactions promoted by phosphonium species.
研究了由磷介导的羧酸活化作用形成酸酐。在各种体系下,取决于试剂的反应性,在碱的存在下苯甲酸的活化导致苯甲酸酐以不同的速率形成。使用Ph 3 P–I 2 / Et 3 N组合,大多数芳酸在5–10分钟内即可高产率转化为相应的酸酐。然而,对于硝基取代的衍生物,出乎意料的是,N,N分离了-二乙酰胺而没有酸酐形成。这些结果表明取代基在控制这些潜在的副反应中具有显着的作用,其可显着影响由phospho物种促进的酰化反应的产率。
Redox-Neutral ortho Functionalization of Aryl Boroxines via Palladium/Norbornene Cooperative Catalysis
作者:Renhe Li、Feipeng Liu、Guangbin Dong
DOI:10.1016/j.chempr.2019.02.005
日期:2019.4
cooperative catalysis, also known as the Catellani reaction, has become an increasingly useful method for site-selective arenefunctionalization; however, certain constraints still exist because of its intrinsic mechanistic pathway. Herein, we report a redox-neutral ortho functionalization of aryl boroxines via Pd/NBE catalysis. An electrophile, such as carboxylic acid anhydrides or O-benzoyl hydroxylamines,
Catalytic Parallel Kinetic Resolution under Homogeneous Conditions
作者:Trisha A. Duffey、James A. MacKay、Edwin Vedejs
DOI:10.1021/jo100695z
日期:2010.7.16
Two complementary chiral catalysts, the phosphine 8d and the DMAP-derived ent-23b, are used simultaneously to selectivelyactivate a mixture of two different achiral anhydrides as acyl donors under homogeneous conditions. The resulting activated intermediates 25 and 26 react with the racemic benzylic alcohol 5 to form enantioenriched esters (R)-24 and (S)-17 by fully catalyticparallelkinetic resolution
两种互补的手性催化剂,膦8d和 DMAP 衍生的ent - 23b,同时用于在均相条件下选择性活化作为酰基供体的两种不同非手性酸酐的混合物。所得活化中间体25和26与外消旋苯甲醇5反应,通过完全催化平行动力学拆分(PKR)形成对映体富集的酯( R ) -24和( S ) -17。对于 PKR 过程,芳酰基酯 ( R )- 24以近乎理想的对映选择性获得,但 ( S)- 17被大约污染。8% 的次要对映异构体 ( R ) -17来自第二个途径,通过形成混合酸酐27并在8d激活。
Construction of Hetero[<i>n</i>]rotaxanes by Use of Polyfunctional Rotaxane Frameworks
Heterorotaxanes, one class of topological organic structures, have attracted increasing interesting during the past two decades. In general, two types of heterorotaxane structures exist, one in which two or more different macrocycles are threaded onto one dumbbell-shaped molecule and the other where one macrocycle is threaded onto two or more different dumbbell-shaped molecules. In comparison to these
Nickel-Catalyzed Three-Component Reductive Alkylacylation of Electron-Deficient Activated Alkenes
作者:Lin Wang、Chuan Wang
DOI:10.1021/acs.orglett.0c03210
日期:2020.11.20
alkylacylation of electron-deficient activated alkenes with tertiary alkyl bromides and acid anhydrides. This method enables the efficient preparation of a variety of ketones with broad substrate scope and high functionality tolerance starting from simple precursors. On the basis of the preliminary mechanistic investigations, a catalytic cycle involving the synergistic interaction of nickel, zinc, and MgCl2