26059-21-2Relevant academic research and scientific papers
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.
Asymmetric reduction of aromatic heterocyclic ketones with bio-based catalyst Lactobacillus kefiri P2
Bayda?, Yasemin,Kalay, Erbay,?ahin, Engin
, p. 1147 - 1155 (2020/10/06)
Abstract: Chiral heterocyclic secondary alcohols have received much attention due to their widespread use in pharmaceutical intermediates. In this study, Lactobacillus kefiri P2 biocatalysts isolated from traditional dairy products, were used to catalyze the asymmetric reduction of prochiral ketones to chiral secondary alcohols. Secondary chiral carbinols were obtained by asymmetric bioreduction of different prochiral substrates with results up to > 99% enantiomeric excess (ee). (R)-1-(benzofuran-2-yl)ethanol 5a, which can be used in the synthesis of pharmaceuticals such as bufuralols potent nonselective β-blockers antagonists, Amiodarone (cardiac anti-arrhythmic), and Benziodarone (coronary vasodilator), was produced in gram-scale, high yield and enantiomerically pure form using L. kefiri P2 biocatalysts. The gram-scale production was carried out, and 9.70?g of (R)-5a in enantiomerically pure form was obtained in 96% yield. Also, production of (R)-5a in terms of yield and gram scale through catalytic asymmetric reduction using the biocatalyst was the highest report so far. This is a cost-effective, clean and eco-friendly process for the preparation of chiral secondary alcohols compared to chemical processes. From an environmental and economic perspective, this biocatalytic method has great application potential, making it a green and sustainable way of synthesis. Graphical Abstract: [Figure not available: see fulltext.]
Light-driven MPV-type reduction of aryl ketones/aldehydes to alcohols with isopropanol under mild conditions
Cao, Dawei,Xia, Shumei,Pan, Pan,Zeng, Huiying,Li, Chao-Jun,Peng, Yong
supporting information, p. 7539 - 7543 (2021/10/12)
Alcohols are versatile structural motifs of pharmaceuticals, agrochemicals and fine chemicals. With respect to green chemistry, the development of more sustainable and cost-efficient processes for converting ketones/aldehydes to alcohols is highly desired. Herein, a direct light-driven strategy for reducing ketones/aldehydes to alcohols using isopropanol as the reducing agent and solvent, in the presence of t-BuOLi, under an air atmosphere at room temperature is developed. This operationally simple light-promoted Meerwein-Ponndorf-Verley (MPV) type reduction can be used to produce various benzylic alcohol derivatives as well as applied to bioactive molecules and PEEK model compounds, demonstrating its application potential.
Asymmetric Transfer Hydrogenation of Aryl Heteroaryl Ketones using Noyori-Ikariya Catalysts
Zheng, Ye,Martinez-Acosta, Jaime A.,Khimji, Mohammed,Barbosa, Luiz C. A.,Clarkson, Guy J.,Wills, Martin
, p. 4384 - 4391 (2021/08/23)
A range of ketones flanked by a combination of an aromatic and a heterocyclic ring (furan, thiophene, N-methylimidazole) were reduced under asymmetric transfer hydrogenation (ATH) conditions. Using a range of [(arene)Ru(TsDPEN)Cl] precatalysts, including tethered derivatives, the reduction enantioselectivity was high (up to 99 % ee) in cases where the aromatic ring contained an ortho-substituent. The enantioselectivity is influenced by a combination of steric and electronic factors which for the furan and thiophene series, follow literature precedents. In the case of the N-methylimidazole-containing ketones, an unexpected switch in enantioselectivity took place upon variation of the opposing aromatic group. Pyrrole- containing ketones were resistant to reduction. This study demonstrates the asymmetric transfer hydrogenation (ATH) of a range of hindered heterocyclic ketones, in high conversion and ee, using Noyori-Ikariya catalysts.
Binaphthyl-prolinol chiral ligands: Design and their application in enantioselective arylation of aromatic aldehydes
Yao, Chao,Chen, Yaoqi,Sun, Ruize,Wang, Chao,Huang, Yue,Li, Lin,Li, Yue-Ming
supporting information, p. 3644 - 3655 (2021/05/04)
Binaphthyl-prolinol ligands were designed and applied in enantioselective arylation of aromatic aldehydes and sequential arylation-lactonization of methyl 2-formylbenzoate. Under optimized conditions, the reactions provided the desired diarylmethanols and 3-aryl phthalides in up to 96% yields with up to 99% ee and up to 89% yields with up to 99% ee, respectively. In particular, essentially optically pure 3-aryl phthalides (over 99% ee) were obtained in large quantities through recrystallization. This journal is
Bulky N-Heterocyclic-Carbene-Coordinated Palladium Catalysts for 1,2-Addition of Arylboron Compounds to Carbonyl Compounds
Okuda, Yuta,Nagaoka, Masahiro,Yamamoto, Tetsuya
, p. 6291 - 6300 (2020/11/30)
The synthesis of primary, secondary, and tertiary alcohols by the 1,2-addition of arylboronic acids or boronates to carbonyl compounds, including unactivated ketones, using novel bulky yet flexible N-heterocyclic carbene (NHC)-coordinated 2,6-di(pentan-3-yl)aniline (IPent)-based cyclometallated palladium complexes (CYPs) as catalysts is reported. The PhS-IPent-CYP-catalyzed reactions are efficient at low catalyst loadings (0.02–0.3 mol% Pd), and the exceptional catalytic activity for 1,2-addition is attributed to the steric bulk of the NHC ligand. These reactions can yield a wide range of functionalized benzylic alcohols that are difficult to synthesize by classical protocols using highly active organomagnesium or lithium reagents.
Isosterically designed chiral catalysts: Rationale, optimization and their application in enantioselective nucleophilic addition to aldehydes
Gao, En,Li, Qiao,Duan, Lili,Li, Lin,Li, Yue-Ming
supporting information, (2020/10/20)
Proline-based N,N′-dioxide ligands were designed on the basis of isosteric approach, and were successfully applied in enantioselective nucleophilic addition to aldehydes. In the presence of 10 mol% of chiral ligand 1b, enantioselective addition of diethylzinc to aldehydes provided the corresponding secondary alcohols in up to 90% isolated yield and up to 99% ee. Similarly, using 3e as chiral ligand, enantioselective arylation and alkynylation of aldehydes also proceeded readily, leading to the desired chiral alcohols in up to 92% isolated yield at 99% ee and 80% isolated yields and up to 84% ee, respectively. The current work would shed light on expanding the structure diversity in the design of chiral ligands and chiral catalysts.
Photoenzymatic Catalysis Enables Radical-Mediated Ketone Reduction in Ene-Reductases
Sandoval, Braddock A.,Kurtoic, Sarah I.,Chung, Megan M.,Biegasiewicz, Kyle F.,Hyster, Todd K.
supporting information, p. 8714 - 8718 (2019/05/28)
Flavin-dependent ene-reductases (EREDs) are known to stereoselectively reduce activated alkenes, but are inactive toward carbonyls. Demonstrated here is that in the presence of photoredox catalysts, these enzymes will reduce aromatic ketones. Mechanistic experiments suggest this reaction proceeds through ketyl radical formation, a reaction pathway that is distinct from the native hydride-transfer mechanism. Furthermore, this reactivity is accessible without modification of either the enzyme or cofactors, allowing both native and non-natural mechanisms to occur simultaneously. Based on control experiments, we hypothesize that binding to the enzyme active site attenuates the reduction potential of the substrate, enabling single-electron reduction. This reactivity highlights opportunities to access new catalytic manifolds by merging photoredox catalysis with biocatalysis.
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.
