3- Chloro-4-nitropyridine-l-oxide

Azathianthrene (382) was prepared in good yield via the corresponding A-oxide 381, obtained by treating 3-chloro-4-nitropyridine-l-oxide (271) with... 

Talik studied the behavior of 3-chloro-4-nitropyridine-l-oxide with various reagents, and showed that sodium methoxide causes replacement of the nitro group, while amines, on the other hand, effect displacement of the halogen. 

The A -oxide function is retained on treatment with nitric and sulfuric acids at somewhat lower temperatures. Thus Talik and Talik prepared 3-chloro-4-nitro-pyridine-1-oxide (84.5%) and 3-iodo-4-nitropyridine-l-oxide (56.4%) with this reagent at steam-bath temperature. 

A full description of work on the Tschitschibabin amination already mentioned has been published 253, piperidine replaces the halogen atom from 3-fluoro- and 3-chloro-4-nitropyridine 1-oxide, whilst with cold sodium methoxide the former gives 3,4-dimethoxypyridine l-oxide 254,... 

Derivatives such as 3-fluoro-4-nitropyridine [13505-01 -6] (396) or the 1-oxide [769-54-0] (397) have been used to characteri2e amino acids and peptides. 5-Eluoro-3-pyridinemethanol [22620-32-2] has been patented as an antihpolytic agent (398). A promising antidepressant, l-(3-fluoro-2-pyridyl)pipera2ine hydrochloride [85386-84-1] is based on 2-chloro-3-fluoropyridine [17282-04-1] (399). 

Chloropyridine-l-oxide when heated with 30% aqueous methylamine at 140° for 18 hours gives 4-methylaminopyridine-l-oxide. Several substituted 4-methylaminopyridines are similarly prepared. 2-Propylaminopyridine and 2-phenethylaminopyiidine are obtained by heating 2-bromopyridine with propylamine and phenethylamine, respectively. 2-Bromopyridine also reacts with 1-aminoindane to give 2-(l-indanylamino)pyridine. 2,6-Di-chloropyridine reacts with butylamine to give 2-butylamino-6-chloropyri-dine. 2-Benzylamino-3-nitropyridine and 2-(chlorobenzylamino)-3-nitro-pyridine are readily prepared from 2-chloro-3-nitropyridine with benzyl amine and p-chlorobenzyl amine, respectively. ... 

Chloro- and bromoaminopyridines are oxidized by persulfuric acid at 0° to their nitro derivatives thus, 3-chloro-, and 3-bromo-4-aminopyridine are converted to the respective 3-halo-4-nitropyridines. However, 4-araino-3-iodo-pyridine is not oxidized under these conditions. 4-Amino-2,3,5,6-tetrafluoro-pyridine is difficult to oxidize and requires refluxing peroxytrifiuoroacetic acid for 22 hours in order to yield the 4-nitro derivative. Potassium bromate has been used to oxidize S-amino-3-methyl-2-pyridone, but the product was not a nitro compound instead 3-hydroxy-6-methyl-2-aza-l,4-benzoquinone-4-(2,6-di-hydroxy-5-methyl-3-pyridyl)imine (IX-S7) was obtained. ... 

Nitro-3-picoline (MI-368) is hydrolyzed on standing to l-(3 -methyl-4 -pyridyl)-3-methyl-4-pyridone and 3-methyl-4-pyridone. 4-Nitropyridine and benzyl bromide give iV-benzyl-3,5-dibromo-4-pyridone (MI-369) in 33% yield. The quaternary salt first formed is hydrolyzed to the 4-pyridone. Oxidation of hydrogen bromide by the nitrous acid product provides the bromine and water. The yield is increased to 71%by the addition of bromine. 3,5-Dibromo-4-chloro-pyridine and benzyl bromide in base also give XII-369. Similarly, 3-methyl-4-nitropyridine and benzyl bromide give W-benzyl-3-bromo-5-methyl-4-... 

Amino-2- and -6-methylpyridine have been prepEired by catalytic hydrogenation of the corresponding 4-chloro-3-nitropicoline l-oxides3 <, and 2-amino-3,5-diethoxypyridine from the nitro-oxide by reduction with iron and acetic acid but, of course, the use of pyridine 1-oxides as a source of aminopyridines has become of importance only since the discovery that nitration occurs readily at C(4) (p. 174). 4-Nitropyridine 1-oxides have been reduced to 4-aminopyridine 1-oxides by ammonium sulphide and by catalytic hydrogenation " 40i , 637 and to 4-aminopyridines by... 

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