14178-29-1Relevant academic research and scientific papers
From Pyridine- N-oxides to 2-Functionalized Pyridines through Pyridyl Phosphonium Salts: An Umpolung Strategy
Bugaenko, Dmitry I.,Yurovskaya, Marina A.,Karchava, Alexander V.
supporting information, p. 6099 - 6104 (2021/08/03)
The reactions of pyridine-N-oxides with Ph3P under the developed conditions provide an unprecedented route to (pyridine-2-yl)phosphonium salts. Upon activation with DABCO, these salts readily serve as functionalized 2-pyridyl nucleophile equivalents. This umpolung strategy allows for the selective C2 functionalization of the pyridine ring with electrophiles, avoiding the generation and use of unstable organometallic reagents. The protocol operates at ambient temperature and tolerates sensitive functional groups, enabling the synthesis of otherwise challenging compounds.
Visible-Light-Mediated C-H Alkylation of Pyridine Derivatives
Rammal, Fatima,Gao, Di,Boujnah, Sondes,Gaumont, Annie-Claude,Hussein, Aqeel A.,Lakhdar, Sami
supporting information, p. 7671 - 7675 (2020/10/09)
We report herein a visible-light-mediated C-H alkylation of pyridine derivatives that proceeds by simple combination of a large variety of N-alkoxypyridinium ions with alkanes in the presence of 2 mol % of fac-Ir(ppy)3 under blue illumination. The mild reaction conditions together with the high group functional tolerance make of this process a useful synthetic platform for the construction of structurally strained heterocycles. Detailed mechanistic investigations, including density functional theory calculations and quantum yield measurement, allowed us to understand factors controlling the reactivity and the selectivity of the reaction.
Reaction of Pyridine-N-Oxides with Tertiary sp2-N-Nucleophiles: An Efficient Synthesis of Precursors for N-(Pyrid-2-yl)-Substituted N-Heterocyclic Carbenes
Bugaenko, Dmitry I.,Karchava, Alexander V.,Yurovskaya, Marina A.
supporting information, p. 5777 - 5782 (2020/12/01)
N-(Pyrid-2-yl)-substituted azolium and pyridinium salts, precursors for hybrid NHC-containing ligands, were obtained with excellent regioselectivity, employing a deoxygenative CH-functionalization of pyridine-N-oxides with substituted imidazoles, thiazoles, and pyridine. Unlike the traditional SNAr-based methods, this approach provides high yields for substrates bearing substituents of different electronic nature. The utility of azolium and pyridinium salts thus prepared was also highlighted by the synthesis of pyridyl-substituted imidazolyl-2-thione, benzodiazepine as well as 2-aminopyridines.
Nickel-catalyzed C–H trifluoromethylation of pyridine N-oxides with Togni's reagent
Gao, Xianying,Geng, Yang,Han, Shuaijun,Liang, Apeng,Li, Jingya,Zou, Dapeng,Wu, Yangjie,Wu, Yusheng
supporting information, p. 1551 - 1554 (2018/03/23)
The first nickel-catalyzed C–H trifluoromethylation of pyridine N-oxides with Togni's reagent has been achieved. Trifluoromethylation proceeds smoothly under mild conditions with moderate functional group compatibility. Notable advantages of this method include the using of low cost of nickel catalyst, and its simple convenient operation.
Copper-Catalyzed Aerobic Oxygenation of Benzylpyridine N-Oxides and Subsequent Post-Functionalization
Sterckx, Hans,Sambiagio, Carlo,Médran-Navarrete, Vincent,Maes, Bert U. W.
supporting information, p. 3226 - 3236 (2017/09/13)
A copper-catalyzed aerobic oxidation of benzylpyridine N-oxides is reported. The N-oxide moiety acts as a built-in activator for the benzylic methylene oxidation, without requirement of additives. Reaction conditions were identified which suppress undesired benzoylpyridine formation via N-deoxygenation involving intermolecular oxygen transfer. The versatility of the N-oxide group of the benzoylpyridine N-oxide reaction products for post-functionalization of the pyridine ring is demonstrated through efficient C–C, C–N, C–O and C–Cl bond forming procedures, with both nucleophiles and electrophiles. Finally, the applicability of the new synthetic methodology is demonstrated in an alternative route towards the antihistaminic drug Acrivastine via three consecutive N-oxide activated C–H functionalization processes, starting from picoline N-oxide. (Figure presented.).
Kinetics of reductive N-O bond fragmentation: The role of a conical intersection
Lorance, Edward D.,Kramer, Wolfgang H.,Gould, Ian R.
, p. 15225 - 15238 (2007/10/03)
N-alkoxyheterocycles can act as powerful one-electron acceptors in photochemical electrontransfer reactions. One-electron reduction of these species results in formation of a radical that undergoes N-O bond fragmentation to form an alkoxy radical and a neutral heterocycle. The kinetics of this N-O bond fragmentation reaction have been determined for a series of radicals with varying substituents and extents of delocalization. Rate constants varying over 7 orders of magnitude are obtained. A reaction potential energy surface is described that involves avoidance of a conical intersection. A molecular basis for the variation of the reaction rate constant with radical structure is given in terms of the relationship between the energies of the important molecular orbitals and the reaction potential energy surface. Ab initio and density functional electronic structure calculations provide support for the proposed reaction energy surface.
2-halo-pyridines
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, (2008/06/13)
2-Halo-pyridines of the general formula I STR1 wherein X is Cl or Br; A is =0 or STR2 Ar is phenyl or substituted phenyl of the general formula STR3 in which n is 0, 1, 2 or 3; R is alkyl C1-4, alkoxy C1-4, phenoxy, alkylthio C1-4, halogen especially F and Cl, OH or C6 H5 ; and their salts, addition compounds and precursors (prodrugs). Furthermore the invention is directed to the production of these compounds and pharmaceuticals containing them.
