20461-30-7Relevant articles and documents
SYN REGIOSELECTIVITY OF THE HYDROPEROXIDATION OF CYCLO-ALKENES WITH SINGLET OXYGEN
Jefford, Charles W.,Rimbault, Christian G.
, p. 91 - 94 (1981)
The regioselectivity of hydroperoxidation of 1-alkylcycloalkenes is rationalized in terms of the formation of a zwitterionic peroxide.
Oxygen Quenching of Electronically Excited Hexanuclear Molybdenum and Tungsten Halide Clusters
Jackson, Julie A.,Turro, Claudia,Newsham, Mark D.,Nocera, Daniel G.
, p. 4500 - 4507 (1990)
Quenching of the electronically excited Y6(2-) (M = Mo(II), W(II), X,Y = Cl,Br,I) ions by molecular oxygen has been investigated.Stern- Volmer analysis of emission intensity and lifetime data reveals that the rate constants for oxygen quenching of the Y6(2-) ions are similar (kqobs = 8.1(37) * 1E7 M-1 s-1) with the exception of the Y6(2-) clusters, which exhibit significantly greater quenching rates (kqobs = 2.1(5) * 1E9 M-1 s-1).Photosensitized oxidation of 1-methylcyclohexene and 1,2-dimethylcyclohexene by all Y6(2-) clusters yields products expected for the reaction of the olefins with singlet oxygen.No evidence of radical autooxidation products were detected.However, the measured quantum yields for the photooxidation of 2,3-diphenyl-p-dioxene by only the Y6(2-) (M = no W; X = no I) clusters are in agreement with the values calculated from a kinetic scheme involving the exclusive production of singlet oxygen by direct energy transfer; observed quantum yields of Y6(2-) -photosensitized reactions are not consistent with this scheme.One explanation for the enhanced oxygen quenching rates of the Y6(2-) excited states (Y6(2-)(excit)) and anomalous observed quantum yields is the contribution of an electron-transfer pathway to the quenching reaction.Transient absorption spectra for the reaction between W6I14(2-)(excit.) and oxygen, however, do not display transients attributable to electron-transfer products.Accordingly, we ascribe the enhanced quenching rate of Y6(2-)(excit.) by oxygen to greater adiabaticity of the energy-transfer reactions of these ions as compared to their homologous cluster counterparts.The absence of an electron-transfer contribution to the Y6(2-)-cluster photosensitized production of 1O2 (Y6(2-)(excit.) + O2 -> Y6(1-) + O2(1-) -> Y6(2-) + 1O2) parallels the results observed for the photosensitized production of 1O2 by RuL3(2+) (L = plypyridyl) systems, which also produce singlet oxygen exclusively by energy transfer despite the existence of potential electron-transfer pathway.
CHOLINE METABOLISM INHIBITORS
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Page/Page column 50; 104, (2020/07/05)
The present disclosure relates to compounds, compositions and methods for inhibiting choline metabolism, e.g., conversion of choline to trimethylamine. Disclosed herein are compounds, compositions, and methods for inhibiting choline metabolism, e.g., conversion of choline to TMA. Also disclosed herein are compounds, methods and compositions for inhibiting choline metabolism by gut microbiota resulting in reduction in the formation of trimethylamine (TMA) and trimethylamine N-oxide (TMAO).
Combining Photo-Organo Redox- and Enzyme Catalysis Facilitates Asymmetric C-H Bond Functionalization
Zhang, Wuyuan,Fueyo, Elena Fernandez,Hollmann, Frank,Martin, Laura Leemans,Pesic, Milja,Wardenga, Rainer,H?hne, Matthias,Schmidt, Sandy
supporting information, p. 80 - 84 (2019/01/04)
In this study, we combined photo-organo redox catalysis and biocatalysis to achieve asymmetric C–H bond functionalization of simple alkane starting materials. The photo-organo catalyst anthraquinone sulfate (SAS) was employed to oxyfunctionalise alkanes to aldehydes and ketones. We coupled this light-driven reaction with asymmetric enzymatic functionalisations to yield chiral hydroxynitriles, amines, acyloins and α-chiral ketones with up to 99 % ee. In addition, we demonstrate functional group interconversion to alcohols, esters and carboxylic acids. The transformations can be performed as concurrent tandem reactions. We identified the degradation of substrates and inhibition of the biocatalysts as limiting factors affecting compatibility, due to reactive oxygen species generated in the photocatalytic step. These incompatibilities were addressed by reaction engineering, such as applying a two-phase system or temporal and spatial separation of the catalysts. Using a selection of eleven starting alkanes, one photo-organo catalyst and 8 diverse biocatalysts, we synthesized 26 products and report for the model compounds benzoin and mandelonitrile > 97 % ee at gram scale.
