- N,N-Dimethylformamide as Hydride Source in Nickel-Catalyzed Asymmetric Hydrogenation of α,β-Unsaturated Esters
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Asymmetric transfer hydrogenation of α,β-unsaturated esters is realized by using a nickel/bisphosphine catalyst and N,N-dimethylformamide (DMF) as the hydride source.
- Guo, Siyu,Zhou, Jianrong
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- Novel riboswitch-binding flavin analog that protects mice against Clostridium difficile infection without inhibiting cecal flora
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Novel mechanisms of action and new chemical scaffolds are needed to rejuvenate antibacterial drug discovery, and riboswitch regulators of bacterial gene expression are a promising class of targets for the discovery of new leads. Herein, we report the characterization of 5-(3-(4-fluorophenyl)butyl)-7,8-dimethylpyrido[3,4-b]quinoxaline-1,3(2H,5H)-dione (5FDQD) - an analog of riboflavin that was designed to bind riboswitches that naturally recognize the essential coenzyme flavin mononucleotide (FMN) and regulate FMN and riboflavin homeostasis. In vitro, 5FDQD and FMN bind to and trigger the function of an FMN riboswitch with equipotent activity. MIC and time-kill studies demonstrated that 5FDQD has potent and rapidly bactericidal activity against Clostridium difficile. In C57BL/6 mice, 5FDQD completely prevented the onset of lethal antibiotic-induced C. difficile infection (CDI). Against a panel of bacteria representative of healthy bowel flora, the antibacterial selectivity of 5FDQD was superior to currently marketed CDI therapeutics, with very little activity against representative strains from the Bacteroides, Lactobacillus, Bifidobacterium, Actinomyces, and Prevotella genera. Accordingly, a single oral dose of 5FDQD caused less alteration of culturable cecal flora in mice than the comparators. Collectively, these data suggest that 5FDQD or closely related analogs could potentially provide a high rate of CDI cure with a low likelihood of infection recurrence. Future studies will seek to assess the role of FMN riboswitch binding to the mechanism of 5FDQD antibacterial action. In aggregate, our results indicate that riboswitch-binding antibacterial compounds can be discovered and optimized to exhibit activity profiles that merit preclinical and clinical development as potential antibacterial therapeutic agents.
- Blount, Kenneth F.,Megyola, Cynthia,Plummer, Mark,Osterman, David,O'Connell, Tim,Aristoff, Paul,Quinn, Cheryl,Chrusciel, R. Alan,Poel, Toni J.,Schostarez, Heinrich J.,Stewart, Catherine A.,Walker, Daniel P.,Wuts, Peter G.M.,Breaker, Ronald R.
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supporting information
p. 5736 - 5746
(2015/09/15)
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- Lipase catalysed kinetic resolutions of 3-aryl alkanoic acids
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Hydrolase catalysed kinetic resolutions leading to a series of 3-aryl alkanoic acids (≥94% ee) are described. Hydrolysis of the ethyl esters with a series of hydrolases was undertaken to identify biocatalysts that yield the corresponding acids with excellent enantiopurity in each case. Steric and electronic effects on the efficiency and enantioselectivity of the biocatalytic transformation were also explored.
- Deasy, Rebecca E.,Brossat, Maude,Moody, Thomas S.,Maguire, Anita R.
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scheme or table
p. 47 - 61
(2011/04/18)
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- Crucial role of elusive isomeric η-complexes in gas-phase electrophilic aromatic alkylations
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The kinetics and stereochemistry of the protonation-induced unimolecular isomerization of (R)-1-D1-3-(p-fluorophenyl)butane have been investigated in the gas phase at 40-100 °C and 70-760 Torr. This process leads to the formation of the relevant meta and ortho isomers with partial racemization of the migrating sec-butyl moiety. Complete racemization is observed, instead, when the isomerization reaction involves a 1,2-H shift in the moving alkyl group. These results, together with the relevant activation parameters, fully confirm the previous evidence of the occurrence in the alkyl cation/arene PES of noncovalent η-type intermediates of defined structure and stability, lying well below the classical π-complexes, as confirmed by ab initio calculations. Their crucial role in determining the positional selectivity of gas-phase electrophilic aromatic substitutions clearly emerges from the comparison of the present results with the site selectivity measured in the corresponding bimolecular arene alkylation carried out at the same temperatures and pressures.
- Marcantoni, Enrico,Roselli, Graziella,Lucarelli, Laura,Renzi, Gabriele,Filippi, Antonello,Trionfetti, Cristiano,Speranza, Maurizio
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p. 4133 - 4141
(2007/10/03)
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- Bicyclic amide derivatives and their use as muscle relaxants
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Novel compounds of formula (1) together with their salts and solvates have a number of uses in medicine, in particular as central muscle relaxants.
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- Bicyclic amide derivatives and their use as muscle relaxants
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Novel compounds of formula (I) STR1 wherein R1, R2, R3 and R4 are each selected from hydrogen and fluoro and at least one and not more than two is fluoro; R5 is selected from hydrogen and C1 -C4 alkyl; R6 is selected from hydrogen, C1 -C4 ally and hydroxy; or R5 and R6 together with the ring carbon form a carbonyl group; R7 is selected from hydrogen and hydroxy, R8 and R9 are each selected from hydrogen, C1 -C4 alkyl and cyclo(C3 or C4) alkyl or together with the nitrogen form a morpholino group; and X is selected from a bond, methylene and --O-- and is always a bond or --O-- when any of R5, R6 and R7 is other than hydrogen and is always a bond when R5 and R6 together with the ring carbon form a carbonyl group; and their salts and solvates have a number of uses as central muscle relaxants. In particular, treatment of conditions associated with abnormally raised skeletal muscle tone. They are of special value in the relaxation of skeletal muscle in spastic, hypertonic and hyperkinetic conditions.
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