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
Palladium-catalyzed enantioselective allylic alkylation of trifluoromethyl group substituted racemic and acyclic unsymmetrical 1,3-disubstituted allylic esters with malonate anions
We examined the palladium-catalyzedallylic alkylation of trifluoromethyl group-substituted racemic and acyclic unsymmetrical 1,3-disubstituted allylic benzoate with a malonate anion, and succeeded in obtaining an enantiomerically enriched product in high yields with high ee values through the dynamic kinetic asymmetric transformation (DYKAT). The best result was attained by the [Pd(C3H5)(cod)]BF4/(S)-tol-BINAP
我们研究了三氟甲基取代的外消旋和无环不对称1,3-二取代的烯丙基苯甲酸酯与丙二酸阴离子的钯催化的烯丙基烷基化,并通过动态动力学不对称转化成功获得了高收率,高ee值的对映体富集产品。 (DYKAT)。在BSA或DMAP作为碱的情况下,通过[Pd(C 3 H 5)(cod)] BF 4 /(S)-tol-BINAP可获得最佳结果。
Organocatalytic Synthesis of α-Trifluoromethyl Allylboronic Acids by Enantioselective 1,2-Borotropic Migration
作者:Sybrand J. T. Jonker、Ramasamy Jayarajan、Tautvydas Kireilis、Marie Deliaval、Lars Eriksson、Kálmán J. Szabó
DOI:10.1021/jacs.0c09923
日期:2020.12.23
Chiral α-substituted allylboronic acids were synthesized by asymmetric homologation of alkenylboronic acids using CF3/TMS-diazomethanes in the presence of BINOLcatalyst and ethanol. The chiral α-substituted allylboronic acids were reacted with aldehydes or oxidized to alcohols in situ with a high degree of chirality transfer. The oxygen-sensitive allylboronic acids can be purified via their isolated
Preparation of phosphonium salt from (S)-trifluoropropene oxide and wittig type reactions
作者:Toshio Kubota、Masahiro Yamamoto
DOI:10.1016/s0040-4039(00)92255-x
日期:1992.4
triphenylphosphine in the presence of trifluoroacetic acid to afford the corresponding β-hydroxyalkyl phosphonium salt. Wittig type reaction of aldehydes with the salt under basic condition readily occurred to form optically active α-trifluoromethylated allylic alcohols. The trans-selectivity of these reactions were discussed.
(R;E)-3,3,3-Trifluoroprop-1-enylp-tolylsulphoxide, prepared in three steps from ethyl trifluoroacetate, showed a high degree of diastereoselectivity in Michaeladditionreactions with enolates; by this means, optically active trifluoromethylated organic molecules can be obtained readily in high yield as well as in high optical purity.