- How Metal Ion Lewis Acidity and Steric Properties Influence the Barrier to Dioxygen Binding, Peroxo O-O Bond Cleavage, and Reactivity
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Herein we quantitatively investigate how metal ion Lewis acidity and steric properties influence the kinetics and thermodynamics of dioxygen binding versus release from structurally analogous Mn-O2 complexes, as well as the barrier to Mn peroxo O-O bond cleavage, and the reactivity of Mn oxo intermediates. Previously we demonstrated that the steric and electronic properties of MnIII-OOR complexes containing N-heterocyclic (NAr) ligand scaffolds can have a dramatic influence on alkylperoxo O-O bond lengths and the barrier to alkylperoxo O-O bond cleavage. Herein, we examine the dioxygen reactivity of a new MnII complex containing a more electron-rich, less sterically demanding NAr ligand scaffold, and compare it with previously reported MnII complexes. Dioxygen binding is shown to be reversible with complexes containing the more electron-rich metal ions. The kinetic barrier to O2 binding and peroxo O-O bond cleavage is shown to correlate with redox potentials, as well as the steric properties of the supporting NAr ligands. The reaction landscape for the dioxygen chemistry of the more electron-rich complexes is shown to be relatively flat. A total of four intermediates, including a superoxo and peroxo species, are observed with the most electron-rich complex. Two new intermediates are shown to form following the peroxo, which are capable of cleaving strong X-H bonds. In the absence of a sacrificial H atom donor, solvent, or ligand, serves as a source of H atoms. With TEMPOH as sacrificial H atom donor, a deuterium isotope effect is observed (kH/kD = 3.5), implicating a hydrogen atom transfer (HAT) mechanism. With 1,4-cyclohexadiene, 0.5 equiv of benzene is produced prior to the formation of an EPR detected MnIIIMnIV bimetallic species, and 0.5 equiv after its formation.
- Yan Poon, Penny Chaau,Dedushko, Maksym A.,Sun, Xianru,Yang, Guang,Toledo, Santiago,Hayes, Ellen C.,Johansen, Audra,Piquette, Marc C.,Rees, Julian A.,Stoll, Stefan,Rybak-Akimova, Elena,Kovacs, Julie A.
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- Multiple Paths for Photo-methylation and -methoxylation of Methyl 2-Pyridinecarboxylate in Methanol
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UV-irradiation of methyl 2-pyridinecarboxylate in methanol in the absence of added acid brings about methylation at the 5-position via the excitation of C=O of the ester group, while in the presence of added acid the 4-position of the pyridine ring is methylated.In the presence of sulfuric acid methoxylation via an excimer is dominant over methylation.In the presence of hydrochloric acid methylation via chlorine atoms becomes dominant.
- Sugiyama, Toru,Furihata, Toshikazu,Takagi, Kyoko,Sato, Michitsugu,Akiyama, Shinya,et al.
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- EFFECTS OF ADDITIVES ON PHOTO-METHOXYLATION OF METHYL 2-PYRIDINECARBOXYLATE IN ACIDIC METHANOLIC SOLUTIONS. PROMOTION BY 4-SUBSTITUTED PYRIDINES.
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The rate of photo-methoxylation of methyl 2-pyridinecarboxylate(1) in acidic methanol is accelerated by 4-substituted pyridines and their analogs, 4,4 prime -bipyridine and pyrazine. The photo-methoxylation of 1 is not promoted by triplet sensitizers, electron donors, or electron acceptors. Detailed analyses on the 1-4-pyridine-carbonitrile(3) system including wavelength dependence lead to a mechanism for the promotion via an excited complex formed from an excited 1 and 3 in the ground state.
- Sugimori,Ogishima,Miyazawa,Hasegawa,Suzuki
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- Synthesis method of 6-methoxy picolinic acid methyl ester
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The invention relates to a synthetic method of 6-methoxy picolinic acid methyl ester. The invention mainly solves the technical problems of expensive reagent and difficult post-treatment in the existing synthesis method. According to the technical scheme, the synthesis method of the 6-methoxy picolinic acid methyl ester is characterized by comprising the following steps: in a high-pressure kettle, taking 6-methoxy-1-bromopyridine as an initial raw material, taking dimethyl sulfoxide and methanol as solvents, adding a palladium catalyst, adding organic alkali, introducing carbon monoxide, performing pressurizing and heating until the reaction is finished, and carrying out treatment so as to obtain the methyl 6methoxypicolinate.
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Paragraph 0012; 0015-0018
(2021/05/01)
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- Pd/C-Catalyzed methoxycarbonylation of aryl chlorides
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A new protocol for the methoxycarbonylation of aryl chlorides has been developed. Various methyl benzoates were produced in good to excellent yields. Several parameters are crucial for the success of this procedure: 1) the usage of LiOMe as the base or co-nucleophile which facilitate the carbonylative transformation; 2) employing Pd/C as the catalyst to prevent the palladium reduced by MeOH and subsequent agglomerate; 3) CO concentration, excessive CO concentration will directly lead to the termination of the reaction.
- Ai, Han-Jun,Franke, Robert,Wu, Xiao-Feng
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- Pyrazole bipyridone compounds, intermediates, and preparation method and application for pyrazole bipyridone compounds
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The invention discloses pyrazole bipyridone compounds. The pyrazole bipyridone compounds have structures as shown in a general formula (1) and a general formula (2) which are described in the specification or pharmaceutically acceptable salts or solvates
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Paragraph 0058-0061
(2019/11/29)
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- FUSED PYRIMIDINE DERIVATIVES HAVING INHIBITORY ACTIVITY ON FMS KINASES
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Disclosed are a fused pyrimidine derivative of formula (I), and a pharmaceutically acceptable salt, stereoisomer, hydrate and solvate thereof, which have an excellent inhibitory activity on FMS kinases, and a pharmaceutical composition comprising the same is effective in preventing or treating diseases caused by abnormal activation of FMS kinases such as immunologic diseases, metabolic diseases, inflammatory diseases, cancers and tumors.
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Page/Page column 34
(2014/01/17)
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- IMIDAZOTRIAZINONE COMPOUNDS
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The present invention provides imidazotriazinone compounds which are inhibitors of phosphodiesterase 9 and pharmaceutically acceptable salt thereof. The present invention further provides processes, pharmaceutical compositions, pharmaceutical preparations and pharmaceutical use of the compounds in the treatment of PDE9 associated diseases or disorders in mammals, including humans.
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Paragraph 0525; 0526
(2013/10/08)
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- IMIDAZOTRIAZINONE COMPOUNDS
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The present invention provides imidazotriazinone compounds which are inhibitors of phosphodiesterase 9. The present invention further provides processes, pharmaceutical compositions, pharmaceutical preparations and pharmaceutical use of the compounds in the treatment of PDE9 associated diseases or disorders in mammals, including CNS or neurodegeneration disorder.
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Page/Page column 86
(2012/04/10)
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- SUBSTITUTED N-(1H-INDAZOL-4-YL)IMIDAZO[1, 2-A]PYRIDINE-3- CARBOXAMIDE COMPOUNDS AS CFMS INHIBITORS
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Compounds of Formula (I): and pharmaceutically acceptable salts thereof in which R1, R2, R3, R4 and R5 have the meanings given in the specification, are inhibitors of cFMS and are useful in the treatment of bone-related diseases, cancer, autoimmune disorders, inflammatory diseases, cardiovascular diseases and pain.
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Page/Page column 93
(2011/07/09)
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- Regioselective nucleophilic addition to pyridinium salts: A new route to substituted dihydropyridones
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"Chemical Equation Presented" The regioselective addition of nucleophiles to pyridinium salts generates an intermediate enol-ether, which can be hydrolyzed in situ to provide a range of dihydropyridones. Certain Grignards have shown inherent differences i
- Donohoe, Timothy J.,Connolly, Matthew J.,Walton, Lesley
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supporting information; experimental part
p. 5562 - 5565
(2010/02/28)
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- The ammonia-free partial reduction of substituted pyridinium salts
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This paper reports a study into the partial reduction of N-alkylpyridinium salts together with subsequent elaboration of the intermediates thus produced. Activation of a pyridinium salt by placing an ester group at C-2, allows the addition of two electron
- Donohoe, Timothy J.,Johnson, Dale J.,MacE, Laura H.,Thomas, Rhian E.,Chiu, Jessica Y. K.,Rodrigues, Jason S.,Compton, Richard G.,Banks, Craig E.,Tomcik, Peter,Bamford, Mark J.,Ichihara, Osamu
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p. 1071 - 1084
(2007/10/03)
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- MULTIPLE PATHS FOR PHOTOALKYLATION OF PYRIDINECARBOXYLIC ESTERS IN ALCOHOLS
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Photochemical substitution of ring hydrogen of pyridinecarboxylic esters by alkyl groups derived from solvent alcohols occurs in several paths: 1) alkylation initiated by excited carbonyl moiety of the ester group and 2) alkylation initiated by the excitation of the ?-electronic system of the pyridine ring.In the photoreaction of methyl 3-pyridinecarboxylate in acidic methanol, three types of excited state (two triplet states for alkylation and a singlet state for alkoxylation) contribute simultaneously.
- Sugiyama, Toru,Tobita, Estuo,Takagi, Kyoko,Sato, Michitsugu,Kumagai, Yasuyuki,et al.
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p. 131 - 134
(2007/10/02)
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