A kinetic resolution of tertiary nitroaldols derived from simple ketones is described. Mixed BINOL/biphenol La-Li heterobimetallic complexes gave the best selectivity in retro-nitroaldol reactions of racemic tertiary nitroaldols. By using a mixture of La-Li3-(1a)3 complex (LLB 2a) and La-Li3-(1b)3 (LLB* 2b) complex in a ratio of 2/1, chiral tertiary nitroaldols were obtained in 80-97% ee and 30-47% recovery yield.
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http://dx.doi.org/10.1021/ja064858l | DOI Listing |
Deuterium (H, D) is a stable isotope of hydrogen (H). Deuterium-incorporated (labelled) compounds are widely utilized in various scientific fields such as mechanistic studies of organic reactions, elucidation of drug metabolism, application as tracers for microanalysis. Recently, development of heavy drugs and molecular imaging using techniques such as neutron scattering and Raman spectroscopy are spotlighted.
View Article and Find Full Text PDFJ Am Chem Soc
September 2018
Institute of Microbial Chemistry (BIKAKEN), 3-14-23 Kamiosaki, Shinagawa-ku , Tokyo 141-0021 , Japan.
A rare-earth metal/alkali metal bimetallic catalyst proved particularly effective for enantioselectively coupling nitroalkanes and α-keto esters in an anti-selective manner to afford synthetically versatile, densely functionalized, and optically active α-nitro tertiary alcohols. A chiral diamide ligand captured two distinct metal cations, giving rise to a catalytically competent solid-phase heterobimetallic catalyst by simple mixing via self-assembly. The advantage of the solid-phase asymmetric catalyst was realized by successful application to the enantio- and diastereoselective reaction in a continuous-flow platform.
View Article and Find Full Text PDFDalton Trans
June 2017
Department of Chemistry, Indian Institute of Technology, Kanpur, UP-208016, India.
A three-dimensional NbO type porous metal-organic framework 1 containing both tertiary amine groups and paddle wheel dinuclear Cu(COO) secondary building units as the active centre was synthesized at room temperature. The activated framework 1' can be used as an efficient heterogeneous catalyst for the synthesis of quinoline derivatives by the Friedländer reaction and for the synthesis of β-nitroalcohols by the Henry (nitroaldol) reaction. This MOF-based heterogeneous catalyst is easily recycled and reused further without losing its structural integrity and catalytic activity.
View Article and Find Full Text PDFChemSusChem
June 2017
Department of Chemistry, University of Rostock, Albert-Einstein-Str. 3a, 18059, Rostock, Germany.
CO -induced switchable tertiary amine-based organocatalysts were investigated for an efficient catalyst and product separation by its different partitioning between an organic and carbonated water phase. In this case study, the switching ability of eight tertiary amine-based catalysts between the organic and water phase by addition or removal of CO was investigated. Here, the catalyst switched both nearly completely (99.
View Article and Find Full Text PDFOrg Lett
February 2014
Departament de Química Orgànica, Facultat de Química-Universitat de València, C/Dr. Moliner 50, E-46100Burjassot (València), Spain.
The direct asymmetric Henry reaction with prochiral ketones, leading to tertiary nitroaldols, is an elusive reaction so far limited to a reduced number of reactive substrates such as trifluoromethyl ketones or α-keto carbonyl compounds. Expanding the scope of this important reaction, the direct asymmetric addition of nitromethane to 2-acylpyridine N-oxides catalyzed by a BOX-Cu(II) complex to give the corresponding pyridine-derived tertiary nitroaldols having a quaternary stereogenic center with variable yields and good enantioselectivity, is described.
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