662136-54-1Relevant academic research and scientific papers
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.
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.).
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.
Chiral thiophosphoramide catalyzed asymmetric aryl transfer reactions for the synthesis of functional diarylmethanols
Wang, Yabai,Zong, Hua,Huang, Huayin,Song, Ling
, p. 90 - 97 (2017/01/12)
In this investigation, chiral thiophosphoramide 3d was easily prepared from chiral (1R,2R)-1,2-diphenylethylenediamine and then applied as an efficient chiral ligand in the catalytic asymmetric arylation reactions of various aromatic aldehydes. The corresponding diarylmethanol products were produced with good to excellent yields (up to 98%) and enantioselectivities (up to 94%). The recovery of chiral ligand 3d could be as high as 96%.
Nickel(0)-Catalyzed Enantio- and Diastereoselective Synthesis of Benzoxasiloles: Ligand-Controlled Switching from Inter- to Intramolecular Aryl-Transfer Process
Kumar, Ravindra,Hoshimoto, Yoichi,Yabuki, Hayato,Ohashi, Masato,Ogoshi, Sensuke
, p. 11838 - 11845 (2015/09/28)
A highly enantioselective synthesis of 3-aryl-, vinyl-, and alkynyl-2,1-benzoxasiloles (up to 99.9% ee and 99% yield) was achieved via the sequential activation of an aldehyde and a silane by nickel(0). This strategy was applied to a simultaneous generation of carbon- and silicon-stereogenic centers with excellent selectivity (dr = 99:1) via diastereotopic aryl transfer. Initial mechanistic studies revealed the complete switching of an aryl-transfer process from an intermolecular (racemic synthesis in the presence of IPr) to an intramolecular (enantioselective synthesis using chiral NHC, L5) fashion. A plausible rationale for the switching of the aryl-transfer process is given by a preliminary DFT calculation, which suggests that the coordination of 1 to the nickel(0)/L5 fragment in an 2-arene:2-aldehyde fashion would be a key to the intramolecular process, while the formation of the corresponding intermediate is not possible in the presence of IPr. Owing to the chemically labile nature of its C-Si and O-Si bonds, enantioenriched benzoxasiloles are utilized for the synthesis of chiral building blocks and antihistaminic and anticholinergic drug molecules such as (R)-orphenadrine and (S)-neobenodine with no erosion of the enantiomeric excess.
Synthesis of Ar-BINMOL ligands by [1,2]-wittig rearrangement to probe their catalytic activity in 1,2-addition reactions of aldehydes with Grignard reagents
Zheng, Long-Sheng,Jiang, Ke-Zhi,Deng, Yuan,Bai, Xing-Feng,Gao, Guang,Gu, Feng-Lei,Xu, Li-Wen
, p. 748 - 750 (2013/03/28)
We have demonstrated a highly diastereoselective synthesis of optically pure Ar-BINMOL-derived diols and their analogues. The present study demonstrates a unique cascade chirality transfer in a [1,2]-Wittig rearrangement that leads to chiral diols with three stereogenic centers, which include a chiral sp 3 center at the alcohol and C2-axial chirality. Screening these ligands in the arylation of aromatic aldehydes with Grignard reagents shows that the naphthyl-substituted BINMOL promotes the aryl transfer reaction in good yields (70-92 %) and moderate-to-good enantioselectivities (up to 72 % ee), and a series of control experiments substantiates that the axial chirality and the chiral sp3 center at the alcohol of the Ar-BINMOLs are the pivotal enantioselectivity-controlling structure elements. In addition, this study demonstrated the importance of the chiral sp3 center at the alcohol on Ar-BINMOL for the aryl transfer reaction. Finally, we found that the chiral Ar-BINMOL ligand 2h mediated the titanium-promoted 1,2-addition of MeMgBr to aldehydes to give the desired products in good yields with excellent enantioselectivities (up to 92 % ee). Ar-BINMOL ligands: A new diastereoselective synthesis of optically pure Ar-BINMOL-derived diols and their analogues has been established through cascade chirality transfer of a [1,2]-Wittig rearrangement. The axial and sp3 central chirality of Ar-BINMOLs are the pivotal enantioselectivity-controlling structure elements in the 1,2-addition of aldehydes with Grignard reagents. Copyright
Chiral triphenylprolinol ligands for the efficient catalytic asymmetric arylation of aldehydes
Moro, Angelica Venturini,Tiekink, Edward R. T.,Zukerman-Schpector, Julio,Luedtke, Diogo S.,Correia, Carlos Roque D.
experimental part, p. 3696 - 3703 (2010/09/05)
The synthesis of new chiral amino alcohols by Heck arylation of an enecarbamate is described. These compounds were used as chiral ligands for the catalytic asymmetric arylation of aldehydes and can be easily recovered. Chiral, nonracemic diarylmethanols were obtained in high yields and enantioselectivities.
Method for inquiring into optical resolution factor, method for judging optical resolution possibility, and method for designing optical resolution
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Page/Page column 17, (2008/06/13)
[PROBLEM TO BE SOLVED]: To provide a method for inquiring into optical resolution factor which can be easily pried from the calculation result obtained by a quantum chemistry calculation concerned with the difference of the physico-chemical quality that influences the separation process and condition of each optical isomer contained in optical isomer mixture, a method for judging optical resolution possibility, and by applying this judging method, to provide a method for designing definite optical resolution using an appropriate asymmetry auxiliary group. [SOLUTION]: The method for inquiring into optical resolution factor which can be pried from the calculation result obtained by a quantum chemistry calculation concerned with the difference of the physico-chemical quality that influences the separation process and condition of each optical isomer contained in optical isomer mixture, the method for judging optical resolution possibility of the optical isomer from this inquiry result, and the method of optical resolution of optical isomer mixture using this judgment method.
