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。
Highly stereoselective asymmetric Michael addition reactions employing (R;E)-3,3,3-trifluoroprop-1-enyl p-tolyl sulphoxide
(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.
Synthesis of <scp>Planar‐Chiral</scp> [2.2]<scp>Paracyclophane‐Based Oxazole‐Pyrimidine</scp> Ligands and Application in <scp>Nickel‐Catalyzed</scp> 1,<scp>2‐Reduction</scp> of α,<scp>β‐Unsaturated</scp> Ketones
structure and large steric hindrance performed successfully in nickel-catalyzed asymmetric 1,2-reduction of α,β-unsaturatedketones, affording the chiral allylic alcohols with up to 99% yield and 99% ee. Meanwhile, this reduction reaction could be conducted on gram-scale without loss of activity and enantioselectivity, and the chiral ligand could be conveniently recovered with high yield.
A Facile Stereocontrolled Synthesis of <i>anti</i>-α-(Trifluoromethyl)-β-amino Alcohols
作者:G. K. Surya Prakash、Mihirbaran Mandal、Stefan Schweizer、Nicos A. Petasis、George A. Olah
DOI:10.1021/ol000195f
日期:2000.10.1
[GRAPHICS]A short stereocontrolled preparation of anti-alpha-(trifluoromethyl)-beta-amino alcohols is described, involving an initial CF3 transfer to cinnamaldehyde and a one-step, three-component condensation of 3,3,3-trifluorolactic aldehyde, an alkenyl (aryl) boronic acid, and an amine. Applying this methodology to chiral 3,3,3-trifluorolactic aldehyde allowed us to generate an amino alcohol enantioselectively in 92% ee.