Stereoselective Formation of Trisubstituted Vinyl Boronate Esters by the Acid-Mediated Elimination of α-Hydroxyboronate Esters
作者:Weiye Guan、Alicia K. Michael、Melissa L. McIntosh、Liza Koren-Selfridge、John P. Scott、Timothy B. Clark
DOI:10.1021/jo500773t
日期:2014.8.1
trisubstituted vinyl boronate esters with moderate to good yields and selectivity. Addition of tosic acid to the crude diboration products provides the corresponding vinyl boronate esters upon elimination. The trisubstituted vinyl boronate esters are formed as the (Z)-olefin isomer, which was established by subjecting the products to a Suzuki–Miyaura coupling reaction to obtain alkenes of known geometry
铜催化酮的二硼化,然后是酸催化的消除,导致形成 1,1-二取代和三取代乙烯基硼酸酯,具有中等至良好的产率和选择性。将甲苯磺酸加入粗二硼化产物中,消除后得到相应的硼酸乙烯酯。三取代的乙烯基硼酸酯形成为 ( Z )-烯烃异构体,这是通过将产物进行 Suzuki-Miyaura 偶联反应以获得已知几何形状的烯烃来建立的。
作者:Wei Wei、Xi-Jie Dai、Haining Wang、Chenchen Li、Xiaobo Yang、Chao-Jun Li
DOI:10.1039/c7sc04207h
日期:——
Natural availability of carbonyl groups offers reductive carbonyl coupling tremendous synthetic potential for efficient olefin synthesis, yet the catalytic carbonyl cross-coupling remains largely elusive. We report herein such a reaction, mediated by hydrazine under ruthenium(II) catalysis. This method enables facile and selective cross-couplings of two unsymmetrical carbonyl compounds in either an
羰基的自然可用性为有效的烯烃合成提供了还原性羰基偶联的巨大合成潜力,但催化羰基的交叉偶联仍然很难实现。我们在本文中报道了在钌(II)催化下由肼介导的这种反应。该方法能够以分子间或分子内的方式使两种不对称羰基化合物容易且选择性地交叉偶联。此外,该化学物质可容纳多种底物,在温和的反应条件下以良好的官能团耐受性进行,并产生化学计量的良性副产物。重要的是,KO t Bu和双齿膦dmpe的共存对于这种转化至关重要。
Visible-Light Photoredox Catalyzed Dehydrogenative Synthesis of Allylic Carboxylates from Styrenes
The visible-light photoredox/[Co(III)] cocatalyzed dehydrogenative functionalization of cyclic and acyclic styrylderivatives with carboxylic acids is documented. The methodology enables the chemo- and regioselective allylic functionalization of styrylcompounds, leading to allylic carboxylates (32 examples) under stoichiometric acceptorless conditions. Intermolecular as well as intramolecular variants
Mechanistic Switch via Subtle Ligand Modulation: Palladium-Catalyzed Synthesis of α,β-Substituted Styrenes via CH Bond Functionalization
作者:Areli Flores-Gaspar、Ruben Martin
DOI:10.1002/adsc.201100140
日期:2011.5
new catalyst system able to efficiently perform the synthesis of styrenes via CH bond functionalization and a subtle ligand modification are described. The high level of activity achieved allows for the synthesis of highly functionalized α,β‐substituted styrenes, even the elusive E‐configured trisubstitutedolefins, in a regio‐ and stereoselective manner. Mechanistic experiments allowed for the identification
Studies in Acyl C−H Activation via Aryl and Alkyl to Acyl “Through Space” Migration of Palladium
作者:Tanay Kesharwani、Akhilesh K. Verma、Daniel Emrich、Jeffrey A. Ward、Richard C. Larock
DOI:10.1021/ol900940k
日期:2009.6.18
Examples of the 1,4-migration of a palladium moiety in aryl- and alkylpalladium intermediates to the acyl position of an aldehyde or formamide have been observed. The resulting acylpalladium intermediate can undergo ester or carbamate formation by reaction with an alcohol; decarbonylation, followed by beta hydride elimination to an alkene; reaction with an organomercurial to form an ester; or alkene insertion. Deuterium-labeling studies have been used to confirm the palladium migration mechanism.