نتایج جستجو برای: enantioselectivity
تعداد نتایج: 1696 فیلتر نتایج به سال:
We have found that O-monoacyltartaric acids catalyze asymmetric conjugate addition of boronic acids to enones with good enantioselectivity, and the 3,5-di(tert-butyl)benzoyl group provides the best results among the acyl groups examined.
Trichlorosilyl triflate-promoted directed cross-aldol reaction between ketones in the presence of a chiral phosphine oxide as an organocatalyst is described. This is the first enantioselective cross-aldol reaction between simple ketones with good enantioselectivity.
Asymmetric addition of arylboronates to aryl-substituted cyclic ketimines proceeded in the presence of a rhodium catalyst coordinated with a chiral diene ligand to give high yields of sulfamidates and sulfamides with high enantioselectivity (up to 99% ee).
Enantioselective alkylation of β-keto phosphonates with diaryl methanols in the presence of catalytic amounts of copper(II) trifluoromethanesulfonate and an optically active ligand gives the corresponding alkylated products in good to high yields with a high enantioselectivity.
[reaction: see text]. A novel catalytic system for asymmetric hydrogenation of functionalized ketones has been developed using a Pd/bisphosphine complex as the catalyst in 2,2,2-trifluoroethanol. The reaction exhibits high enantioselectivity, and up to 92.2% ee was obtained.
When Boc-L-Val-OH was used as a ligand for the enantioselective Pd(II)-catalyzed annulation of N,N-substituted aminomethyl ferrocene derivatives with diarylethynes, ferrocenes with planar chirality could be achieved with excellent enantioselectivity (up to 99% ee).
The introduction of nitrogen to carbonyl groups is considered both challenging and highly desirable by those who work in the field organic synthesis. In this study, a diphenylethylenediamine-derived catalyst demonstrating N-selectivity was designed using quantum calculation for nitroso aldol reaction. reductive monoalkylation (R,R)-(+)-1,2-diphenylethylenediamine afforded an chiral diamine high...
Different deep eutectic solvent (DES) mixtures were studied as reaction media for the continuous synthesis of enantiomerically enriched products by testing different experimental set-ups. L-Proline-catalysed cross-aldol reactions were efficiently performed in continuo, with high yield (99%), anti-stereoselectivity, and enantioselectivity (up to 97% ee). Moreover, using two different DES mixture...
Research to develop highly versatile, chiral, heterogeneous catalysts for asymmetric organic transformations, without quenching the catalytic reactivity, has met with limited success. While chiral supramolecular structures, connected by weak bonds, are highly active for homogeneous asymmetric catalysis, their application in heterogeneous catalysis is rare. In this work, asymmetric catalyst was ...
Enantioselective esterification of ibuprofen has been successfully carried out in an organic solvent catalyzed by recombinant APE 1547 (a thermophilic esterase from the archaeon Aeropyrum pernix K1). Here we used microwave irradiation (MW) as the mode of heating to improve the enzyme performance. Under the optimum conditions, the enzyme activity of APE 1547 was 4.16 μmol/mg/h and the enantiosel...
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