362-54-9Relevant articles and documents
Asymmetric Transfer Hydrogenation of Diaryl Ketones with Ethanol Catalyzed by Chiral NCP Pincer Iridium Complexes
Huang, Zheng,Liu, Guixia,Qian, Lu,Tang, Xixia,Wang, Yulei
, (2022/02/23)
The use of a chiral (NCP)Ir complex as the precatalyst allowed for the discovery of asymmetric transfer hydrogenation of diaryl ketones with ethanol as the hydrogen source and solvent. This reaction was applicable to various ortho-substituted diaryl keontes, affording benzhydrols in good yields and enantioselectivities. This protocol could be carried out in a gram scale under mild reaction conditions. The utility of the catalytic system was highlighted by the synthesis of the key precursor of (S)-neobenodine.
Tunable System for Electrochemical Reduction of Ketones and Phthalimides
Chen, Gong,Qiao, Tianjiao,Wang, Yaxin,Zhang, Jian,Zhao, Jianyou
supporting information, p. 3297 - 3302 (2021/10/14)
Herein, we report an efficient, tunable system for electrochemical reduction of ketones and phthalimides at room temperature without the need for stoichiometric external reductants. By utilizing NaN3 as the electrolyte and graphite felt as both the cathode and the anode, we were able to selectively reduce the carbonyl groups of the substrates to alcohols, pinacols, or methylene groups by judiciously choosing the solvent and an acidic additive. The reaction conditions were compatible with a diverse array of functional groups, and phthalimides could undergo one-pot reductive cyclization to afford products with indolizidine scaffolds. Mechanistic studies showed that the reactions involved electron, proton, and hydrogen atom transfers. Importantly, an N3/HN3 cycle operated as a hydrogen atom shuttle, which was critical for reduction of the carbonyl groups to methylene groups.
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.
Method for synthesizing chiral secondary alcohol compound
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Paragraph 0038-0043; 0099-0103, (2021/05/29)
The invention discloses a method for synthesizing a chiral secondary alcohol compound. The method comprises the following step of: reacting a ketone compound in an aprotic organic solvent at room temperature and inert gas atmosphere under the action of a chiral cobalt catalyst and an activating agent by taking a combination of bis(pinacolato)diboron and alcohol or water as a reducing agent to obtain the chiral secondary alcohol compound. According to the method disclosed by the invention, a combination of pinacol diborate and alcohol or water which are cheap, stable and easy to obtain is taken as a reducing agent, and a ketone compound is efficiently reduced to synthesize a corresponding chiral secondary alcohol compound in an aprotic organic solvent under the action of a chiral cobalt catalyst; in a chiral cobalt catalyst adopted by the method, when a chiral ligand is PAOR, an activating agent is NaBHEt3 or NaOtBu and an adopted raw material is aromatic ketone, the yield is 80% or above, and the optical purity is 90% or above; and when the adopted raw material is alkane ketone, the yield can reach 70% or above, and the optical purity can reach 80% or above.
Highly Enantioselective Cobalt-Catalyzed Hydroboration of Diaryl Ketones
Liu, Wenbo,Guo, Jun,Xing, Shipei,Lu, Zhan
supporting information, p. 2532 - 2536 (2020/04/02)
A highly enantioselective cobalt-catalyzed hydroboration of diaryl ketones with pinacolborane was developed using chiral imidazole iminopyridine as a ligand to access chiral benzhydrols in good to excellent yields and ee. This protocol could be carried out in a gram scale under mild reaction conditions with good functional group tolerance. Chiral biologically active 3-substituted phthalide and (S)-neobenodine could be easily constructed through asymmetric hydroboration as a key step.
Redox-driven deracemization of secondary alcohols by sequential ether/O2-mediated oxidation and Ru-catalyzed asymmetric reduction
Yang, Bing,Cui, Peng,Chen, Yongsheng,Liu, Qixing,Zhou, Haifeng
supporting information, (2020/10/14)
The deracemization of benzylic alcohols has been achieved using a redox-driven one-pot two-step process. The racemic alcohols were oxidized by bis(methoxypropyl) ether and oxygen to give the ketone intermediates, followed by an asymmetric transfer hydrogenation with a chiral ruthenium catalyst. This compatible oxidation/reduction process gave the enantiomerically enriched alcohols with up to 95% ee values.
Electrochemical Hydrogenation with Gaseous Ammonia
Li, Jin,He, Lingfeng,Liu, Xu,Cheng, Xu,Li, Guigen
supporting information, p. 1759 - 1763 (2019/01/16)
As a carbon-free and sustainable fuel, ammonia serves as high-energy-density hydrogen-storage material. It is important to develop new reactions able to utilize ammonia as a hydrogen source directly. Herein, we report an electrochemical hydrogenation of alkenes, alkynes, and ketones using ammonia as the hydrogen source and carbon electrodes. A variety of heterocycles and functional groups, including for example sulfide, benzyl, benzyl carbamate, and allyl carbamate were well tolerated. Fast stepwise electron transfer and proton transfer processes were proposed to account for the transformation.
Substituent Position-Controlled Stereoselectivity in Enzymatic Reduction of Diaryl- and Aryl(heteroaryl)methanones
Li, Zhining,Wang, Zexu,Wang, Yuhan,Wu, Xiaofan,Lu, Hong,Huang, Zedu,Chen, Fener
supporting information, p. 1859 - 1865 (2019/03/07)
We report here the discovery of a novel ketoreductase (KRED), named KmCR2, with a broad substrate spectrum on bioreduction of sterically bulky diaryl- and aryl(heteroaryl)methanones. The position of the substituent on aromatic rings (meta versus para or ortho) was revealed to control the stereospecificity of KmCR2. The stereoselective preparation of both enantiomers of diaryl- or aryl(heteroaryl)methanols using strategically engineered substrates with a traceless directing group (bromo group) showcased the potential application of this substrate-controlled bioreduction reaction. The combined use of substrate engineering and protein engineering, was demonstrated to be a useful strategy in efficiently improving stereoselectivity or switching stereopreference of enzymatic processes. (Figure presented.).
Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
supporting information, p. 16490 - 16494 (2019/11/03)
Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
Chiral Lithium Amido Aryl Zincates: Simple and Efficient Chemo- and Enantio-Selective Aryl Transfer Reagents
Chaumont-Olive, Pauline,Rouen, Mathieu,Barozzino-Consiglio, Gabriella,Ben Abdeladhim, Amel,Maddaluno, Jacques,Harrison-Marchand, Anne
supporting information, p. 3193 - 3197 (2019/01/25)
An enantioselective aryl transfer is promoted using chiral tricoordinated lithium amido aryl zincates that are easily accessible reagents and whose chiral appendage is simply recovered for reuse. The arylation reaction is run in good yields (60 % average on twenty substrates) and high enantiomeric excesses (95 % ee average). This occurs whatever the ortho, meta, or para substituent borne by the substrate and a complete chemoselectivity is observed with respect to the aldehyde function. Sensitive groups such as nitriles, esters, ketones, and enolisable substrates resist to the action of the ate reagent, warranting a large scope to this methodology.
