125639-56-7Relevant articles and documents
Visible-Light-Driven Catalytic Deracemization of Secondary Alcohols
Hu, Xile,Zhang, Zhikun
supporting information, p. 22833 - 22838 (2021/09/09)
Deracemization of racemic chiral compounds is an attractive approach in asymmetric synthesis, but its development has been hindered by energetic and kinetic challenges. Here we describe a catalytic deracemization method for secondary benzylic alcohols which are important synthetic intermediates and end products for many industries. Driven by visible light only, this method is based on sequential photochemical dehydrogenation followed by enantioselective thermal hydrogenation. The combination of a heterogeneous dehydrogenation photocatalyst and a chiral molecular hydrogenation catalyst is essential to ensure two distinct pathways for the forward and reverse reactions. These reactions convert a large number of racemic aryl alkyl alcohols into their enantiomerically enriched forms in good yields and enantioselectivities.
Asymmetric Magnesium-Catalyzed Hydroboration by Metal-Ligand Cooperative Catalysis
Falconnet, Alban,Magre, Marc,Maity, Bholanath,Cavallo, Luigi,Rueping, Magnus
supporting information, p. 17567 - 17571 (2019/11/13)
Asymmetric catalysis with readily available, cheap, and non-toxic alkaline earth metal catalysts represents a sustainable alternative to conventional synthesis methodologies. In this context, we describe the development of a first MgII-catalyzed enantioselective hydroboration providing the products with excellent yields and enantioselectivities. NMR spectroscopy studies and DFT calculations provide insights into the reaction mechanism and the origin of the enantioselectivity which can be explained by a metal-ligand cooperative catalysis pathway involving a non-innocent ligand.
Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of Ketones
Liu, Xiaoqin,Wang, Qiaotian,Han, Caifang,Feng, Xiangqing,Du, Haifeng
, p. 663 - 666 (2019/05/21)
A highly enantioselective Piers-type hydrosilylation of simple ketones was successfully realized using a chiral frustrated Lewis pair of tri-tert-butylphosphine and chiral diene-derived borane as catalyst. A wide range of optically active secondary alcohols were furnished in 80%—99% yields with 81%—97% ee's under mild reaction conditions.
Design, synthesis and structure-based optimization of novel isoxazole-containing benzamide derivatives as FtsZ modulators
Bi, Fangchao,Song, Di,Zhang, Nan,Liu, Zhiyang,Gu, Xinjie,Hu, Chaoyu,Cai, Xiaokang,Venter, Henrietta,Ma, Shutao
, p. 90 - 103 (2018/10/04)
Antibiotic resistance among clinically significant bacterial pathogens is becoming a prevalent threat to public health, and new antibacterial agents with novel mechanisms of action hence are in an urgent need. Utilizing computational docking method and structure-based optimization strategy, we rationally designed and synthesized two series of isoxazol-3-yl- and isoxazol-5-yl-containing benzamide derivatives that targeted the bacterial cell division protein FtsZ. Evaluation of their activity against a panel of Gram-positive and -negative pathogens revealed that compounds B14 and B16 that possessed the isoxazol-5-yl group showed strong antibacterial activity against various testing strains, including methicillin-resistant Staphylococcus aureus and penicillin-resistant S. aureus. Further molecular biological studies and docking analyses proved that the compound functioned as an effective inhibitor to alter the dynamics of FtsZ self-polymerization via a stimulatory mechanism, which finally terminated the cell division and caused cell death. Taken together, these results could suggest a promising chemotype for development of new FtsZ-targeting bactericidal agent.
Co6H8(PiPr3)6: A Cobalt Octahedron with Face-Capping Hydrides
Ohki, Yasuhiro,Shimizu, Yuki,Araake, Ryoichi,Tada, Mizuki,Sameera,Ito, Jun-Ichi,Nishiyama, Hisao
supporting information, p. 15821 - 15825 (2016/12/16)
A square-planar Co4amide cluster, Co4{N(SiMe3)2}4(2), and an octahedral Co6hydride cluster, Co6H8(PiPr3)6(4), were obtained from metathesis-type amide to hydride exchange reactions of a CoIIamide complex with pinacolborane (HBpin) in the absence/presence of PiPr3. The crystal structure of 4 revealed face-capping hydrides on each triangular [Co3] face, while the formal CoII2CoI4oxidation state of 4 indicated a reduction of the cobalt centers during the assembly process. Cluster 4 catalyzes the hydrosilylation of 2-cyclohexen-1-one favoring the conjugate reduction. Generation of the catalytically reactive Co cluster species was indicated by a trapping experiment with a chiral chelating agent.
Enantioselective Hydrosilylation of Ketones Catalyzed by a Readily Accessible N-Heterocyclic Carbene-Ir Complex at Room Temperature
Shinohara, Kanako,Kawabata, Shun,Nakamura, Hanako,Manabe, Yoshiki,Sakaguchi, Satoshi
, p. 5532 - 5539 (2014/10/16)
A series of functionalized azolium compounds were synthesized from chiral α-amino acid derivatives such as β-amino alcohols. of hydroxy-amide-functionalized azolium salts thus obtained with Ag2O afforded N-heterocyclic carbene-Ag (NHC-Ag) complexes. Subsequent treatment of the resulting silver compound with [IrCl(cod)]2 yielded monodentate IrCl(cod)(NHC), which was stable in air. The NHC-Ir complex facilitated efficient asymmetric hydrosilylation of ketones using (EtO)2MeSiH under ambient conditions. A chiral ligand containing an isobutyl stereodirecting group was found to be the best ligand for the functionalized NHC-Ir complexes that were examined. A linear relationship was found between the catalyst ee and the product ee. The hydroxy functional group on the NHC ligand side-arm not only induced stereocontrol but also enhanced the reaction rate.
Regio-specific polyacetylenes synthesized from anionic polymerizations of template monomers
Zhang, Yang,Li, Jia,Li, Xiaohong,He, Junpo
, p. 6260 - 6269 (2015/02/19)
Substituted polyacetylenes with alkylphenyl side groups and head-to-head regioregularity were prepared through anionic living polymerization of template monomers and subsequent dehydrogenation process. The template monomers have the structure of 2, 3-disubstituted-1, 3-butadienes prepared by palladium-catalyzed Kumada coupling of the corresponding vinyl bromides. Anionic polymerizations of the template monomers produced narrow disperse substituted polybutadiene precursors with exclusive 1, 4-enchainment. The precursors were converted into soluble polyacetylene derivatives via two methods, e.g., bromination followed by elimination of HBr, and direct dehydrogenation by 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ), both resulting in dark colored products with significant red shift in UV spectra. The obtained head-to-head polyacetylene derivatives exhibited highly thermal stability, possibly due to trans-rich and/or head-to-head chain configurations. The microstructures of the poly(2, 3-dialkylphenyl butadiene) precursors were analyzed in detail using NMR spectroscopy with regard to the solvent effect during polymerization. Block copolymers containing substituted polyacetylene segments were prepared through sequential anionic polymerization of different monomers, followed by dehydrogenation transformation. The present synthesis may serve as a new strategy for tailoring molecular structures of polyacetylene-based polymers by virtue of anionic living polymerization techniques.
Asymmetric hydrosilane reduction of ketones catalyzed by an iridium complex bearing a hydroxyamide-functionalized NHC ligand
Kawabata, Shun,Tokura, Hiromu,Chiyojima, Hiroyuki,Okamoto, Masaki,Sakaguchi, Satoshi
experimental part, p. 807 - 812 (2012/05/04)
An enantioselective hydrosilylation of prochiral ketones was achieved by using a catalytic amount of the readily accessible and air- and moisture-stable iridium complex [IrCl(cod)(NHC)] at room temperature. Copyright
Iron- and cobalt-catalyzed asymmetric hydrosilylation of ketones and enones with bis(oxazolinylphenyl)amine ligands
Inagaki, Tomohiko,Phong, Le Thanh,Furuta, Akihiro,Ito, Jun-Ichi,Nishiyama, Hisao
supporting information; experimental part, p. 3090 - 3096 (2010/08/05)
Chiral bis(oxazolinylphenyl)amines proved to be efficient auxiliary ligands for iron and cobalt catalysts with high activity for asymmetric hydrosilylation of ketones and asymmetric conjugate hydrosilylation of enones.
Preparative asymmetric reduction of ketones in a biphasic medium with an (S)-alcohol dehydrogenase under in situ-cofactor-recycling with a formate dehydrogenase
Gr?ger, Harald,Hummel, Werner,Rollmann, Claudia,Chamouleau, Francoise,Hüsken, Hendrik,Werner, Helge,Wunderlich, Christine,Abokitse, Kofi,Drauz, Karlheinz,Buchholz, Stefan
, p. 633 - 640 (2007/10/03)
The substrate range of a novel recombinant (S)-alcohol dehydrogenase from Rhodococcus erythropolis is described. In addition, an enzyme-compatible biphasic reaction medium for the asymmetric biocatalytic reduction of ketones with in situ-cofactor regeneration has been developed. Thus, reductions of poorly water soluble ketones in the presence of the alcohol dehydrogenase from R. erythropolis and a formate dehydrogenase from Candida boidinii can be carried out at higher substrate concentrations of 10-200 mM. The resulting (S)-alcohols were formed with moderate to good conversion rates, and with up to >99% ee.
