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81.
Enzymatic Desymmetrising Redox Reactions for the Asymmetric Synthesis of Biaryl Atropisomers
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Samantha Staniland Bo Yuan Nelson Giménez‐Agulló Dr. Tommaso Marcelli Dr. Simon C. Willies Dr. Damian M. Grainger Prof. Nicholas J. Turner Prof. Jonathan Clayden 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13084-13088
Atropisomeric biaryls carrying ortho‐hydroxymethyl and formyl groups were made enantioselectively by desymmetrisation of dialdehyde or diol substrates. The oxidation of the symmetrical diol substrates was achieved using a variant of galactose oxidase (GOase), and the reduction of the dialdehydes using a panel of ketoreductases. Either M or P enantiomers of the products could be formed, with absolute configurations assigned by time‐dependent DFT calculations of circular dichroism spectra. The differing selectivities observed with different biaryl structures offer an insight into the detailed structure of the active site of the GOase enzyme. 相似文献
82.
Phenylalanine Ammonia Lyase Catalyzed Synthesis of Amino Acids by an MIO‐Cofactor Independent Pathway
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Sarah L. Lovelock Dr. Richard C. Lloyd Prof. Nicholas J. Turner 《Angewandte Chemie (International ed. in English)》2014,53(18):4652-4656
Phenylalanine ammonia lyases (PALs) belong to a family of 4‐methylideneimidazole‐5‐one (MIO) cofactor dependent enzymes which are responsible for the conversion of L ‐phenylalanine into trans‐cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non‐natural amino acids. Herein the discovery of a previously unobserved competing MIO‐independent reaction pathway, which proceeds in a non‐stereoselective manner and results in the generation of both L ‐ and D ‐phenylalanine derivatives, is described. The mechanism of the MIO‐independent pathway is explored through isotopic‐labeling studies and mutagenesis of key active‐site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1cB elimination mechanism. 相似文献
83.
Reu P. L. Blaysat B. Andó E. Bhattacharya K. Couture C. Couty V. Deb D. Fayad S. S. Iadicola M. A. Jaminion S. Klein M. Landauer A. K. Lava P. Liu M. Luan L. K. Olufsen S. N. Réthoré J Roubin E. Seidl D. T. Siebert T. Stamati O. Toussaint E. Turner D. Vemulapati C. S. R. Weikert T. Witz J. F. Witzel O. Yang J. 《Experimental Mechanics》2022,62(4):639-654
Experimental Mechanics - The DIC Challenge 2.0 follows on from the work accomplished in the first Digital Image Correlation (DIC) Challenge Reu et al. (Experimental Mechanics 58(7):1067, 1). The... 相似文献
84.
InspIRED by Nature: NADPH‐Dependent Imine Reductases (IREDs) as Catalysts for the Preparation of Chiral Amines
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Prof. Dr. Gideon Grogan Prof. Dr. Nicholas J. Turner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):1900-1907
Imine reductases (IREDs) are NADPH‐dependent oxidoreductases that catalyse the asymmetric reduction of cyclic prochiral imines to amines, with excellent stereoselectivity. Since their discovery, stereocomplementary IREDs have been applied to the production of both (S) and (R) cyclic secondary amines, and the expansion in gene sequences recently identified has hinted at new substrate ranges that extend into acyclic imines and even suggest the possibility of asymmetric reductive amination from suitable ketone and amine precursors. Structural studies of various IREDs are beginning to reveal the complexities inherent in determining substrate range, stereoselectivity and mechanism in these enzymes, which represent a valuable emerging addition to the toolbox of available biocatalysts for chiral amine production. 相似文献
85.
The deracemisation and stereoinversion of both cyclic and acyclic DL-alpha-amino acids, using porcine kidney D-amino acid oxidase (DAAO) and a hydride reducing agent (NaCNBH3-NaBH4), has been investigated. 相似文献
86.
Abouderbala LO Belcher WJ Boutelle MG Cragg PJ Dhaliwal J Fabre M Steed JW Turner DR Wallace KJ 《Chemical communications (Cambridge, England)》2002,(4):358-359
A series of podands based on three hydrogen bonding 'arms' have been prepared and their affinities for simple inorganic anions measured. 相似文献
87.
88.
[reaction: see text] The syntheses of 4,4a-didehydrohimbacine and 4,4a-didehydrohimandravine are presented. Key steps include an intramolecular Diels-Alder reaction of a bromopentadienyl acrylate and Suzuki-Miyaura and Stille coupling reactions. 相似文献
89.
High-throughput approaches for the discovery and optimization of new olefin polymerization catalysts
Murphy V Bei X Boussie TR Brümmer O Diamond GM Goh C Hall KA Lapointe AM Leclerc M Longmire JM Shoemaker JA Turner H Weinberg WH 《Chemical record (New York, N.Y.)》2002,2(4):278-289
The discovery of new olefin polymerization catalysts is currently a time-intensive trial-and-error process with no guarantee of success. A fully integrated high-throughput screening workflow for the discovery of new catalysts for polyolefin production has been implemented at Symyx Technologies. The workflow includes the design of the metal-ligand libraries using custom-made computer software, automated delivery of metal precursors and ligands into the reactors using a liquid-handling robot, and a rapid primary screen that serves to assess the potential of each metalligand-activator combination as an olefin polymerization catalyst. "Hits" from the primary screen are subjected to secondary screens using a 48-cell parallel polymerization reactor. Individual polymerization reactions are monitored in real time under conditions that provide meaningful information about the performance capabilities of each catalyst. Rapid polymer characterization techniques support the primary and secondary screens. We have discovered many new and interesting catalyst classes using this technology. 相似文献
90.
Kubo K Akemoto M Anderson S Aoki T Araki S Bane KL Blum P Corlett J Dobashi K Emma P Frisch J Fukuda M Guo Z Hasegawa K Hayano H Higo T Higurashi A Honda Y Iimura T Imai T Jobe K Kamada S Karataev P Kashiwagi S Kim E Kobuki T Kotseroglou T Kurihara Y Kuriki M Kuroda R Kuroda S Lee T Luo X McCormick DJ McKee B Mimashi T Minty M Muto T Naito T Naumenko G Nelson J Nguyen MN Oide K Okugi T Omori T Oshima T Pei G Potylitsyn A Qin Q Raubenheimer T Ross M Sakai H Sakai I Schmidt F Slaton T Smith H 《Physical review letters》2002,88(19):194801
Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping ring which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than 1% of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than 2.8 x 10(-8) rad m at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance. 相似文献