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Patrick Metzner Jean-François Brière Hiroya Takada 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):965-968
Abstract The reaction of novel chiral selenonium and telluronium ylides was investigated with aldehydes and compared to the sulfur analogues. (2R,5R)-2,5-Dimethylselenolane was prepared and reacted as a catalyst for the benzylidenation of aldehydes. Disubstituted epoxides were readily prepared with a (surprising) absence of diastereoselectivity, and with enantiomeric excesses higher than 90%. The reaction of a tellurium analogue, (2S,5S)-2,5-diethyltellurolane, afforded the oxirane in very moderate yield and e.e.'s in the range of 62–82%. Though this was less productive, it is the first report of a chiral telluronium ylide leading to an asymmetric epoxidation of aldehydes. 相似文献
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Devrishi Goswami Srikripa Devarakonda Michael J. Chalmers Bruce D. Pascal Bruce M. Spiegelman Patrick R. Griffin 《Journal of the American Society for Mass Spectrometry》2013,24(10):1584-1592
Application of typical HDX methods to examine intrinsically disordered proteins (IDP), proteins that are natively unstructured and highly dynamic at physiological pH, is limited because of the rapid exchange of unprotected amide hydrogens with solvent. The exchange rates of these fast exchanging amides are usually faster than the shortest time scale (10 s) employed in typical automated HDX-MS experiments. Considering the functional importance of IDPs and their association with many diseases, it is valuable to develop methods that allow the study of solution dynamics of these proteins as well as the ability to probe the interaction of IDPs with their wide range of binding partners. Here, we report the application of time window expansion to the millisecond range by altering the on-exchange pH of the HDX experiment to study a well-characterized IDP; the activation domain of the nuclear receptor coactivator, peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α). This method enabled mapping the regions of PGC-1α that are stabilized upon binding the ligand binding domain (LBD) of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ). We further demonstrate the method’s applicability to other binding partners of the IDP PGC-1α and pave the way for characterizing many other biologically important ID proteins. Figure
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Intensive research in the last two decades on the degradation of commercial plastics has led to the development of new methods of degradation and innumerable experimental techniques to characterize the degraded products. During the period 1970–1980, there have been substantial advances in most of the important aspects of polymer degradation including that induced by heat, light, oxygen, high energy radiation, photooxidation, and biological factors; and accounts have been given at various times of the current position in most of these [1–30]. 相似文献
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ABSTRACT The leaving ability of the benzothiazol-2-ylthio group was applied to the C-alkylation of a 2,3-enopyranoside model structure. Coordination of the organometallic reagent to the thio-heterocyclic moiety was responsible for a stereospecific syn conjugate alkyl attack. 相似文献
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