Nonenzymatic kinetic resolution of racemic 2,2,2-trifluoro-1-aryl ethanol via enantioselective acylation
作者:Qing Xu、Hui Zhou、Xiaohong Geng、Peiran Chen
DOI:10.1016/j.tet.2009.01.058
日期:2009.3
Kineticresolution of a series of 2,2,2-trifluoro-1-aryl ethanol with (R)-benzotetramisole as the catalyst has been investigated. The result showed that when the aryl group in the substrate was a phenyl (or a phenyl substituted by an electron-donating group) or a naphthyl (an extended phenyl) group, the system could give an s value higher than 20. Preparative KR examples demonstrated the applicability
observed in the reduction of hinderedketones such as isopropyl ketone, while the stereoselectivity was inverted in the reduction of ketones with electron-withdrawing atoms such as chlorine. The mechanism for the inversion in stereochemistry was investigated by enzymatic studies. Several enzymes with different stereoselectivities were isolated; one of them catalyzed the reduction of methyl ketones, and another
Chemo- and Enantioselective Addition and β-Hydrogen Transfer Reduction of Carbonyl Compounds with Diethylzinc Reagent in One Pot Catalyzed by a Single Chiral Organometallic Catalyst
作者:Huayin Huang、Hua Zong、Guangling Bian、Ling Song
DOI:10.1021/acs.joc.5b01871
日期:2015.12.18
as the catalyst, the asymmetric β-H transfer reduction of aromatic α-trifluoromethyl ketones and enantioselective addition of aromatic aldehydes with Et2Zn in one pot were successfully realized, affording the corresponding additive products of secondary alcohols in high yields (up to 99%) with excellent enantioselectivities (up to 98% ee) and the reduction products of α-trifluoromethyl alcohols in good
The asymmetric hydrogenation of 2,2,2-trifluoroacetophenones and aryl perfluoroalkyl ketones was developed using a unique, well-defined chloride-bridged dinuclear rhodium(III) complex bearing Josiphos-type diphosphine ligands. These complexes were prepared from [RhCl(cod)]2 , Josiphos ligands, and hydrochloric acid. As catalyst precursors, they allow for the efficient and enantioselective synthesis
Asymmetric trifluoromethylation of aromatic aldehydes by cooperative catalysis with (IPr)CuF and quinidine-derived quaternary ammonium salt
作者:Shaoxiang Wu、Wei Zeng、Qi Wang、Fu-Xue Chen
DOI:10.1039/c2ob26827b
日期:——
A general enantioselective trifluoromethylation of aldehydes has been developed using (IPr)CuF and quinidine-derived quaternary ammonium salt as the cooperative catalyst. Thus, a wide range of aromatic aldehydes have been converted to the corresponding products in up to 92% yield and 81% ee at 2 mol% of catalyst loading. The greatly enhanced activity and enantioselectivity result from the initiative generation of active [(IPr)CuCF3] as well as additional coordination activation of other copper species.