- Exocyclic delocalization at the expense of aromaticity in 3,5-bis(π-donor) substituted pyrazolium ions and corresponding cyclic bent allenes
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Small ring allenes are usually highly strained and highly reactive species, and for a long time considered only as transient intermediates. The recent isolation of a five membered heterocyclic allene 1f has raised questions and debate regarding the factor
- Fernandez, Israel,Dyker, C. Adam,DeHope, Alan,Donnadieu, Bruno,Frenking, Gernot,Bertrand, Guy
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- Facile synthesis of high specific activity 4-[1-14C]butyl-1,2-diphenylpyrazolidine-3,5-dione (phenylbutazone) using nucleophilic substitution
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Metabolism, environmental fate, and low concentration food residue studies would be facilitated by the use of radiolabeled test articles that can be readily quantified within complex matrices. However, radiochemical approaches for such studies require high specific activities to allow analytical detection of correspondingly low masses of test article. The synthesis of high specific activity (>50?μCi/μmol) [14C]-radiolabeled phenylbutazone presents a challenge using existing methodology, mainly due to the low solvent volumes required and vigorous refluxing needed to close the pyrazolidinedione ring. Herein, we report on the significant modification of an existing method that allows the synthesis of low masses of high specific activity (>50?μCi/μmol) [14C]-phenylbutazone under mild conditions with simple purification and high yield. The closure of the pyrazolidinedione ring of 1,2-diphenyl-3,5-pyrazolidinedione was accomplished as a first step with unlabeled 1,2-diphenylhydrazine and diethyl malonate in 32% yield under gram-scale conditions, which avoided the challenges of low solvent use and vigorous refluxing. Low mass of high specific activity n-[1-14C]-butyl bromide was then added via a nucleophilic substitution reaction as a final step. Yields ranged from 65% to 92% during multiple synthetic attempts with unlabeled butyl bromide and were greatly influenced by reaction stoichiometry and the selection of base.
- Singh, Anuradha,Hakk, Heldur,Lupton, Sara J.
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p. 386 - 390
(2018/03/21)
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- Chiral Pincer Carbodicarbene Ligands for Enantioselective Rhodium-Catalyzed Hydroarylation of Terminal and Internal 1,3-Dienes with Indoles
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Catalytic enantioselective addition of N-heteroarenes to terminal and internal 1,3-dienes is reported. Reactions are promoted by 5 mol % of Rh catalyst supported by a new chiral pincer carbodicarbene ligand that delivers allylic substituted arenes in up to 95% yield and up to 98:2 er. Mechanistic and X-ray evidence is presented that supports that the reaction proceeds via a Rh(III)-η3-allyl.
- Marcum, Justin S.,Roberts, Courtney C.,Manan, Rajith S.,Cervarich, Tia N.,Meek, Simon J.
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supporting information
p. 15580 - 15583
(2017/11/14)
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- Pyrazolidine-3,5-diones and 5-hydroxy-1H-pyrazol-3(2H)-ones, inhibitors of UDP-N-acetylenolpyruvyl glucosamine reductases
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A series of pyrazolidine-3,5-dione and 5-hydroxy-1H-pyrazol-3(2H)-one inhibitors of Escherichia coli UDP-N-acetylenolpyruvyl glucosamine reductase (MurB) has been prepared. The 5-hydroxy-1H-pyrazol-3(2H)-ones show low micromolar IC50 values versus E. coli MurB and submicromolar minimal inhibitory concentrations (MIC) against Staphylococcus aureus GC 1131, Enterococcus faecalis GC 2242, Streptococcus pneumoniae GC 1894, and E. coli GC 4560 imp, a strain with increased outer membrane permeability. None of these compounds show antimicrobial activity against Candida albicans, a marker of eukaryotic toxicity. Moreover, these compounds inhibit peptidoglycan biosynthesis, as assessed by measuring the amount of soluble peptidoglycan produced by Streptococcus epidermidis upon incubation with compounds. A partial least squares projection to latent structures analysis shows that improving MurB potency and MIC values correlate with increasing lipophilicity of the C-4 substituent of the 5-hydroxy-1H-pyrazol-3(2H)-one core. Docking studies using FLO and PharmDock produced several binding orientations for these molecules in the MurB active site.
- Gilbert, Adam M.,Failli, Amedeo,Shumsky, Jay,Yang, Youjun,Severin, Anatoly,Singh, Guy,Hu, William,Keeney, David,Petersen, Peter J.,Katz, Alan H.
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p. 6027 - 6036
(2007/10/03)
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- Methine compound, material for organic luminescence element, organic luminescence element using the same
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Disclosed is a novel methine compound, for example, which is represented by the following formula (I): wherein R1, R2, R3, R4and R5each represents a hydrogen atom or a substituent; X represents an oxygen atom, a sulfur atom, or N—R6; Z represents —NR7R8, or —OG; R6, R7and R8each represents a hydrogen atom or a substituent; G represents a hydrogen atom, a cation or a substituent; L1, L2and L3each represents a substituted or unsubstituted methine group; n represents 1 or 2; and W represents an electron attractive group. Also, a material for organic luminescence element is disclosed which is a compound represented by the following formula (II): wherein R1, R2, R3, R4, R5, R6, R7and R8each represents a hydrogen atom or a substituent; R9represents a hydrogen atom or a substituent other than a methyl group; X represents an oxygen atom, a sulfur atom, or N—R10, wherein R10represents a hydrogen atom or a substituent; Z1represents an atomic group necessary for forming a5- or6-membered ring; L1and L2each represents a substituted or unsubstituted methine group; and n represents 1 or 2.
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- Compositions containing pyrazolin-3,5-dione couplers for use in keratin fiber dyeing methods and kits
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The present invention relates to a composition for dyeing keratin fibers, in particular human hair, containing, in a medium which is suitable for dyeing: as coupler, at least one compound of formula: or one of the addition salts thereof with an acid; and at least one oxidation base.
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- Preparation and Evaluation of Electrophilic Derivatives of Phenylbutazone as Inhibitors of Prostaglandin-H Synthase
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The chemical syntheses and biological evaluation of several potential irreversible inhibitors for prostaglandin (PGH) synthase are described.These inhibitors were modeled after the nonsteroidal antiinflammatory (NSAI) drug phenylbutazone(4-n-butyl-1,2-dip
- Vennerstrom, Jonathan L.,Holmes, Thomas J.
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p. 563 - 567
(2007/10/02)
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- IODONIUM DERIVATIVES OF β-DIKETONES. SYNTHESIS AND CHARACTERISTICS OF IODONIUM DERIVATIVES OF 1,2-DIPHENYL-3,5-PYRAZOLIDINEDIONE
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The betaines of 4-phenyliodonio- and 4-(p-methoxyphenyliodonio)-1,2-diphenyl-3,5-pyrazolidinedione were obtained by the reaction of 1,2-diphenyl-3,5-pyrazolinedione with (diacetoxyiodo)arenes in an alkaline medium.During thermal catalytic decomposition in
- Adamsone, B. Ya.,Neiland, O. Ya.,Kampare, R. B.
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p. 771 - 775
(2007/10/02)
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