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排序方式: 共有472条查询结果,搜索用时 437 毫秒
81.
Campbell CD Duguet N Gallagher KA Thomson JE Lindsay AG O'Donoghue AC Smith AD 《Chemical communications (Cambridge, England)》2008,(30):3528-3530
Cascade reaction sequences incorporating N-heterocyclic carbene-based organocatalysis have been developed that allow the direct preparation of a range of (+/-)-4-phenoxycarbonylazlactones in good isolated yields (66-84%) from the corresponding N-p-anisoyl amino acids. 相似文献
82.
Isabelle Gallagher Gabriel S. Koch Fabrice Planchon 《Communications in Mathematical Physics》2016,343(1):39-82
We prove that if an initial datum to the incompressible Navier–Stokes equations in any critical Besov space \({\dot B^{-1+\frac 3p}_{p,q}({\mathbb {R}}^{3})}\), with \({3 < p, q < \infty}\), gives rise to a strong solution with a singularity at a finite time \({T > 0}\), then the norm of the solution in that Besov space becomes unbounded at time T. This result, which treats all critical Besov spaces where local existence is known, generalizes the result of Escauriaza et al. (Uspekhi Mat Nauk 58(2(350)):3–44, 2003) concerning suitable weak solutions blowing up in \({L^{3}({\mathbb R}^{3})}\). Our proof uses profile decompositions and is based on our previous work (Gallagher et al., Math. Ann. 355(4):1527–1559, 2013), which provided an alternative proof of the \({L^{3}({\mathbb R}^{3})}\) result. For very large values of p, an iterative method, which may be of independent interest, enables us to use some techniques from the \({L^{3}({\mathbb R}^{3})}\) setting. 相似文献
83.
Stereospecific construction of substituted piperidines. Synthesis of (-)-paroxetine and (+)-laccarin
Bower JF Riis-Johannessen T Szeto P Whitehead AJ Gallagher T 《Chemical communications (Cambridge, England)》2007,(7):728-730
Short and efficient enantioselective syntheses of (-)-paroxetine and (+)-laccarin are described based on the highly stereospecific cleavage of C(3)-substituted 1,3-cyclic sulfamidates. 相似文献
84.
John F. Gallagher Claire M. Coleman Donal F. O'Shea 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):o149-o151
The molecule of the title compound, C19H27NO3, is essentially planar, with all non‐H atoms within 0.2 Å of the nine‐membered indole plane, except for the three tert‐butyl C atoms. The C5 pentyl chain is in an extended conformation, with three torsion angles of 179.95 (13), 179.65 (13) and −178.95 (15)° (the latter two angles include the C atoms of the C5 chain only). Three intramolecular C—H⋯Ozdbnd;C contacts are present (C⋯O < 3.05 Å and C—H⋯O > 115°), and an intermolecular C—H⋯Ozdbnd;C contact and π–π stacking complete the intermolecular interactions. 相似文献
85.
Simpson GL Gordon AH Lindsay DM Promsawan N Crump MP Mulholland K Hayter BR Gallagher T 《Journal of the American Chemical Society》2006,128(33):10638-10639
The synthesis of a triglycosylated helical foldamer based on a combination of cyclopentyl- and pyrrolidinyl-based amino acids is described. This structure is stable in water, maintaining as it does a series of carbohydrate units in proximity to one another, and represents the basis of a new approach to the study of carbohydrate-carbohydrate interactions. 相似文献
86.
Z Chen C Jing SS Gallagher MP Sheetz VW Cornish 《Journal of the American Chemical Society》2012,134(33):13692-13699
Chemical tags are now viable alternatives to fluorescent proteins for labeling proteins in living cells with organic fluorophores that have improved brightness and other specialized properties. Recently, we successfully rendered our TMP-tag covalent with a proximity-induced reaction between the protein tag and the ligand-fluorophore label. This initial design, however, suffered from slow in vitro labeling kinetics and limited live cell protein labeling. Thus, here we report a second-generation covalent TMP-tag that has a fast labeling half-life and can readily label a variety of intracellular proteins in living cells. Specifically, we designed an acrylamide-trimethoprim-fluorophore (A-TMP-fluorophore v2.0) electrophile with an optimized linker for fast reaction with a cysteine (Cys) nucleophile engineered just outside the TMP-binding pocket of Escherichia coli dihydrofolate reductase (eDHFR) and developed an efficient chemical synthesis for routine production of a variety of A-TMP-probe v2.0 labels. We then screened a panel of eDHFR:Cys variants and identified eDHFR:L28C as having an 8-min half-life for reaction with A-TMP-biotin v2.0 in vitro. Finally, we demonstrated live cell imaging of various cellular protein targets with A-TMP-fluorescein, A-TMP-Dapoxyl, and A-TMP-Atto655. With its robustness, this second-generation covalent TMP-tag adds to the limited number of chemical tags that can be used to covalently label intracellular proteins efficiently in living cells. Moreover, the success of this second-generation design further validates proximity-induced reactivity and organic chemistry as tools not only for chemical tag engineering but also more broadly for synthetic biology. 相似文献
87.
Fiona Brady John F. Gallagher Carol Murphy 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):365-368
The title compounds, C12H13NO4, are derived from l ‐threonine and dl ‐threonine, respectively. Hydrogen bonding in the chiral derivative, (2S/3R)‐3‐hydroxy‐2‐(1‐oxoisoindolin‐2‐yl)butanoic acid, consists of O—Hacid?Oalkyl—H?O=Cindole chains [O?O 2.659 (3) and 2.718 (3) Å], Csp3—H?O and three C—H?πarene interactions. In the (2R,3S/2S,3R) racemate, conventional carboxylic acid hydrogen bonding as cyclical (O—H?O=C)2 [graph set R22(8)] is present, with Oalkyl—H?O=Cindole, Csp3—H?O and C—H?πarene interactions. The COOH group geometry differs between the two forms, with C—O, C=O, C—C—O and C—C=O bond lengths and angles of 1.322 (3) and 1.193 (3) Å, and 109.7 (2) and 125.4 (3)°, respectively, in the chiral structure, and 1.2961 (17) and 1.2210 (18) Å, and 113.29 (12) and 122.63 (13)°, respectively, in the racemate structure. The O—C=O angles of 124.9 (3) and 124.05 (14)° are similar. The differences arise from the contrasting COOH hydrogen‐bonding environments in the two structures. 相似文献
88.
John F. Gallagher Peter T. M. Kenny Michael O'Donohoe 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):e157-e158
The title compound, C13H15N3O7, crystallizes as two independent molecules which differ in their conformation. Intermolecular hydrogen bonding between the amide and carboxylic acid groups as N—H?O=C interactions results in the formation of one‐dimensional chains with N?O distances of 2.967 (6) and 3.019 (6) Å. Neighbouring chains are linked by C=O?H—O interactions to form a two‐dimensional network, with O?O distances of 2.675 (6) and 2.778 (6) Å. 相似文献
89.
90.
The goal of this research is to prepare a series of alloys having sharp, reproducible magnetic transitions for calibrating temperature in thermogravimetry from the magnetic transition temperature of pure cobalt (1121°C) to below room temperature.Alloys in the Ni-Co and Ni-Cu systems were prepared by the thermal decomposition of coprecipitated oxalates in argon. The alloys were subsequently annealed under 5% hydrogen.Magnetic transition temperatures were measured using simultaneous thermomagnetometry/differential thermal analysis. Transition temperatures were corrected using well known meltingpoint standards. Magnetic transition temperatures along with precision are reported as a function of composition. 相似文献