of carboxylic acids. Herein, we reported the development of a palladium-catalyzed highly enantioselective Markovnikov hydroxycarbonylation of vinyl arenes with CO and water. A monodentate phosphoramidite ligand L6 plays vital role in the reaction. The reaction tolerates a range of functional groups, and provides a facile and atom-economical approach to an array of 2-arylpropanoic acids including several
不对称羟基羰基化是合成羧酸的最基本但最具挑战性的方法之一。在此,我们报道了钯催化的乙烯基芳烃与 CO 和水的高度对映选择性马尔可夫尼科夫羟基羰基化的发展。单齿亚磷酰胺配体L6反应中起重要作用。该反应耐受一系列官能团,并为一系列 2-芳基丙酸(包括几种常用的非甾体抗炎药)提供了一种简便且原子经济的方法。该催化体系还使乙烯基芳烃与醇发生不对称马尔科夫尼科夫氢烷氧基羰基化反应,得到 2-芳基丙酸酯。机理研究表明,氢化钯是不可逆的,是区域和对映体决定步骤,而水解/醇解可能是限速步骤。
Cobalt‐Catalyzed Enantioselective Negishi Cross‐Coupling of Racemic α‐Bromo Esters with Arylzincs
enantioselective Negishi cross‐coupling reaction, and the first arylation of α‐halo esters with arylzinc halides, are disclosed. Employing a cobalt‐bisoxazoline catalyst, various α‐arylalkanoic esters were synthesized in excellent enantioselectivities and yields (up to 97 % ee and 98 % yield). A diverse range of functional groups, including ether, halide, thioether, silyl, amine, ester, acetal, amide, olefin
Highly Enantioselective Hydroxycarbonylation and Alkoxycarbonylation of Alkenes using Dipalladium Complexes as Precatalysts
作者:Tina M. Konrad、José A. Fuentes、Alexandra M. Z. Slawin、Matthew L. Clarke
DOI:10.1002/anie.201004415
日期:2010.11.22
Joined at Pd: Novel palladium catalysts like 1, in which the planar‐chiral phosphine acts as a bridging ligand, have been developed. These dimetallic complexes are highlyenantioselective catalysts in the hydroxycarbonylation of alkenes, a reaction that has proven problematic over the years. PTSA=para‐toluenesulfonic acid.
The first iron-catalyzed enantioselective cross-coupling reaction between an organometallic compound and an organic electrophile is reported. Synthetically versatile racemic α-chloro- and α-bromoalkanoates were coupled with aryl Grignard reagents in the presence of catalytic amounts of an iron salt and a chiral bisphosphine ligand, giving the products in high yields with acceptable and synthetically
Kinetic Resolution of α-Substituted Alkanoic Acids Promoted by Homobenzotetramisole
作者:Xing Yang、Vladimir B. Birman
DOI:10.1002/chem.201101028
日期:2011.9.26
classes of substrates, namely, α‐aryl‐, α‐aryloxy/alkoxy‐, α‐halo‐, α‐azido‐, and α‐phthalimido‐alkanoicacids. Under similar conditions, α‐(arylthio/alkylthio)‐alkanoicacids undergo dynamickineticresolution providing corresponding esters in up to 92 % ee and up to 93 % yield.