A Modified Method for the Preparation of 3-Chloro- and 3-Bromopyridines

Specificity of 15N NMR chemical shifts to the nature of substituents and tautomerism in substituted pyridine N-oxides

“…The modified synthesis of 2-acetylaminopyridine N-oxides (2, 4) and 4-, 5-, and 6-methyl-(2-acetylaminopyridine-Noxides) (7,8,9) [8][9][10]13] has been presented previously [14]. By modification of methods by Brown and Adam et al [9,10], a remarkable shortening in reaction time (9 to 2 h) was achieved by substituting acetic acid by acetic anhydride in the reaction.…”

“…The syntheses of 2-amino-5-nitro-(10), 2-amino-5-nitro-3-methyl-(13) and 2-amino-5-nitro-6-methylpyridine N-oxides (14) have been presented previously [16,17]. These compounds were obtained in rearrangement reaction of the corresponding nitraminopyridine N-oxides [16,17].…”

“…In this paper, we present our studies regarding the possible tautomerism in amino and acetylaminopyridine N-oxides because this problem has not yet been unambiguously solved. Another interest lies in the 5-nitro-substituted compounds (10,13,14), where the electron lone pair of amino moiety is involved in the p-electron conjugation with the aromatic ring the nitro group acting as an electron acceptor.…”

“…Otherwise, oxidation would have transformed aminopyridines into nitropyridines [7][8][9][10][11][12][13][14][15]. In hydrolysis, acetylamino derivatives of pyridine N-oxide gave the corresponding amino compounds [7].…”

“…In hydrolysis, acetylamino derivatives of pyridine N-oxide gave the corresponding amino compounds [7]. 2-Amino-and 2-acetylaminopyridine N-oxides as well as their 3-, 4-, 5-, and 6-methyl derivatives are reported in literature [8,9], but their synthesis were greatly improved [14] compared to the earlier reported methods [8][9][10][11][12][13].…”