- Rhodium(III)-Catalyzed Site-Selective C-H Alkylation and Arylation of Pyridones Using Organoboron Reagents
-
In this study we developed a method for the pyridine-directed, rhodium-catalyzed, site-selective C-H alkylation and arylation of pyridones using commercially available trifluoroborate reagents. This simple and versatile transformation proceeded smoothly under relatively mild conditions with perfect site selectivity. The coupling groups in the boron reagents can be extended to primary alkyl, benzyl, and cycloalkyl. Moreover, direct C-H arylation products could also be obtained under similar conditions.
- Peng, Panfeng,Wang, Jiang,Jiang, Hualiang,Liu, Hong
-
-
Read Online
- Controlled oxygen release from pyridone endoperoxides promotes cell survival under anoxic conditions
-
In tissue engineering, survival of larger constructs remains challenging due to limited supply of oxygen caused by a lack of early vascularization. Controlled release of oxygen from small organic molecules represents a possible strategy to prevent cell death under anoxic conditions. A comprehensive study of methylated pyridone-derived endoperoxides has led to the development of water-soluble molecules that undergo retro-Diels-Alder reactions in aqueous environment releasing oxygen in high yield and with half-lives of up to 13 h. These molecules in combination with vitamin C as singlet oxygen quencher significantly improved survival of 3T3 fibroblasts and rat smooth muscle cells challenged with oxygen-depleted conditions.
- Benz, Sebastian,N?tzli, Sarah,Siegel, Jay S.,Eberli, Daniel,Jessen, Henning J.
-
-
Read Online
- Rh(I)-Catalyzed C6-Selective Decarbonylative Alkylation of 2-Pyridones with Alkyl Carboxylic Acids and Anhydrides
-
A Rh-catalyzed chelation-assisted C6-selective C-H activation/alkylation of 2-pyridones with readily available alkyl carboxylic acids or anhydrides is introduced. The reaction proceeds via substrate decarbonylation. This approach merges C-H functionalization with readily available anhydrides, allowing for the efficient synthesis of various C6-alkylated 2-pyridones with good functional group tolerance.
- Fan, Qinghua,Li, Bohan,Li, Huanrong,Walsh, Patrick J.,Xu, Lijin,Xu, Xin,Xu, Xingyu,Yu, Haiyang,Zhao, Haoqiang
-
supporting information
p. 4228 - 4234
(2020/06/27)
-
- Asymmetric Homogeneous Hydrogenation of 2-Pyridones
-
An asymmetric homogeneous hydrogenation of 2(1H)-pyridones has been developed, using a ruthenium complex bearing two chiral N-heterocyclic carbene (NHC) ligands. To the best of our knowledge, the presented reaction is the first example of a homogeneous asymmetric conversion of 2-pyridones into the corresponding enantioenriched 2-piperidones.
- Wysocki, Jedrzej,Schlepphorst, Christoph,Glorius, Frank
-
supporting information
p. 1557 - 1562
(2015/06/30)
-
- Demethylation of methoxypyridines with sodium trimethylsilanethiolate
-
Demethylation of methoxypyridines was accomplished in 55-87percent yield by use of ca. 1.5-2.5 equivalents of NaSSiMe3 in 1,3-dimethyl-2-imidazolidinone at 120-180 deg C.This method was found applicable to a methoxyquinoline and methoxypyridines containing a second substituent, such as Cl, OMe, and COOMe.
- Shiao, Min-Jen,Ku, Wei-Shen,Hwu, Jih Ru
-
p. 323 - 328
(2007/10/02)
-
- The Photolysis of 1-Benzyloxy-2-pyridone and its Methyl Derivatives. Correlation with 1H NMR-derived Ground-state Conformation
-
In addition to methyl substituent effects on the reactivities of the vibrationally unrelaxed excited singlet state of 1-benzyloxy-2-pyridone (1), deuterium isotope effects on the reaction efficiencies of (1) and its methyl derivatives are discussed on the basis of their major ground-state conformations, as analysed by 1H NMR spectroscopy.It is suggested that intramolecular hydrogen abstraction of the benzylic hydrogen by the amido carbonyl oxygen in (1) competes with N-O bond cleavage in polar solvents.Effects exerted by both a methyl group and a non-polar solvent aremanifested by the predominant N-O bond cleavage in the vibrationally 'hot' excited singlet state.
- Sakurai, Tadamitsu,Murakata, Yasukuni,Inoue, Hiroyasu
-
p. 499 - 503
(2007/10/02)
-
- The structures of huperzine A and B, two new alkaloids exhibiting marked anticholinesterase activity
-
Huperzine A and B, two new Lycopodium alkaloids isolated from Huperzia serrata (Thunb.) Trev., are shown to possess structures 1 and 3, respectively, on the basis of chemical and spectroscopic data.
- Liu, Jia-Sen,Zhu, Yuan-Long,Yu, Chao-Mei,Zhou, You-Zuo,Han, Yan-Yi,et al.
-
p. 837 - 840
(2007/10/02)
-
- Nucleophilic Displacement of N-Aryl and Heteroaryl Groups. Part 5. Conversion of 2-Aminopyridines into 2-Pyridones
-
2-Ethoxycarbonyl-1-(2-pyridyl)pyridinium cations (3) (easily prepared from 2-aminopyridine and the appropriate pyrylium salt) are converted by dilute NaOH at 25 deg C into 1-(substituted 2-pyridylcarbonyl)-2-pyridones (7).Compounds (7) are readily hydrolysed to 2-pyridones.
- Katritzky, Alan R.,Awartani, Radi
-
p. 2623 - 2627
(2007/10/02)
-
- The Mechanisms of Thermal Eliminations. Part 11. Rate Data for Pyrolysis of 2-Alkoxypyridines to 2-Pyridone, and of 2-Ethoxypicolines to 2-Picolones: Nature and Polarity of the Transition State
-
The rates of thermal elimination of 2-ethoxy-, 2-isopropoxy-, 2-t-butoxy-pyridine to 2-pyridone and the corresponding alkene, and of the 2-ethoxy derivatives of 3-, 4-, 5-, and 6-methylpyridines to ethylene and the corresponding 2-picolines have been measured over at least 50 deg for each compound, between 585.1 and 721.1 K.The respective log (A/s-1) and Ea/kJ mol-1 values for the former three compounds are 12.20, 196.5; 12.68, 187.6; and 12.33, 161.0, and these are similar to those for the corresponding acetates.The relative rates of the first-order unimolecular decomposition at 600 K are: Et(1.0), Pri(18.0), But(1645) compared with 1.0:28.8:3316 for the acetates.The polarity of the transition state is thus less than for ester elimination.The difference in the rate ratios k(Pri)/k(Et) for alkoxypyridine and acetate pyrolyses is greater than the difference in the k(But)/k(Pri) ratios and is interpreted in terms of the difference in polarity of the transition states for primary, secondary, and tertiary elimination.Methyl substituents in the 3-, 4-, 5-, and 6-positions of the pyridine ring change the rate at 600 K by factors of 1.57, 1.02, 0.74, and 1.08, respectively.These show the decomposition does not take place via N-alkylpyridone tautomers, and that the reaction is, like ester pyrolysis, sterically accelerated.
- Al-Awadi, Nouria,Ballam, John,Hemblade, Paul R.,Taylor, Roger
-
p. 1175 - 1178
(2007/10/02)
-
- SYNTHESIS OF PYRIDINE N-OXIDE-SbCl5 COMPLEXES AND THEIR INTRAMOLECULAR AND OXYGEN-TRANSFER REACTION
-
Mixing with equimolar solutions of pyridine N-oxide or its homologs and SbCl5 in CCl4 deposited 1:1 complexes as colorless crystals in high yield.On thermolysis, these complexes underwent intramolecular oxygen transfer to give selectively the corresponding 2-pyridone derivatives.N,N-Dimethylaniline N-oxide and SbCl5 also gave a crystalline 1:1 complex which on termolysis yield o-dimethylaminophenol in good yield.
- Yamamoto, Jiro,Imagawa, Masahiro,Yamauchi, Sigeyuki,Nakazava, Osamu,Umezu, Masahiro,et al.
-
p. 1871 - 1873
(2007/10/02)
-
- Kinetic Study of the Acid-Promoted Hydrolysis of Some Representative 2-Fluoro Nitrogen Heterocycles
-
The acid-promoted hydrolysis of the 2-fluoro derivatives of pyridine, the four isomeric picolines, quinoline, pyrimidine, 4-methylpyrimidine, and 4,6-dimethylpyrimidine have been studied in hydrochloric acid over the concentration range of 0.05-8.0 F HCl.At each acid concentration, the reactions followed pseudo-first-order kinetics, and at low concentrations of acid, the rate of reaction increased linearly with h0.However, at higher acid concentrations negative deviations from linearity were observed for all the substrates and rate maxima for all but the pyrimidines.These results were correlated with the decline in water activity by means of the Bunnett ω and ω* relationships, as well as the Bunnett-Olsen LFER.The slopes of these correlations were suggestive of a proton transfer role for water in the reactions of the less activated 2-fluoropyridines and of 2-fluoroquinoline, while the correlations indicate a nucleophilic role for water in the reactions of the more highly activated pyrimidines.Entropies of activation, calculated both from the pseudo-first-order rate constants, and from the values of k2* obtained from the intercepts of the LFER plot, were significantly more negative for the pyridine and quinoline systems for the pyrimidines.The above results are interpreted as consistent with nucleophilic attack by water in the rate-determining step for the reaction of the pyrimidines, while for the less activated substrates nucleophilic attack may be assisted by proton transfer to additional water molecules.
- Clark, H. R.,Beth, L. D.,Burton, R. M.,Garrett, D. L.,Miller, A. L.,Muscio, O. J.
-
p. 4363 - 4369
(2007/10/02)
-