8-Nitro pyridine, from

Acylation with acetyl chloride (giving 94) or protonation permits rapid displacement of the nitro group from 4-nitropyridine A-oxide by the weakly nucleophilic chloride Pyridine A-oxide... 

A compound (40), isolated from the reaction between 2-chloro-5-nitro-pyridine and tert-butyl jV-hydroxycarbamate, has been shown to react with benzaldehyde to give 6-nitro-2-phenyl-triazolopyridine (41)53 5-nitro-2-pyridone acts as a leaving group. 

Draw stmctures for the aza-indoles resulting from treatment of 2-methyl-3-nitro- and 4-methyl-3-nitro-pyridines, respectively, with (Et02C)2/Et0Na, followed by H2/Pd-C. Both products have the molecular formula C10H10N2O2. 

Boruah et al. reported a facile and convenient synthesis of pyridines 16 from P-formyl enamides 17 under microwave irradiation employing a Henry reaction <04SL1309>. The author postulates that nitromethane reacts with the formyl group, followed by dehydration and subsequent cyclization and aromatization to yield the nitro-pyridine 16. 

Pyridine is converted into a mixture of the 2- and the 3-nitro derivative under extreme conditions and in poor yield,115b and the three mononitropyridines are better obtained by oxidizing the appropriate aminopyridines with Caro s acid.234-236 Nitration is appreciably smoother, although requiring equally drastic conditions, if substituents such as OH,237 NH2,238 or CH3239 are present in the pyridine nucleus e.g., with potassium nitrate and fuming sulfuric acid 2,4,6-trimethyl- and 2,6-dimethyl-pyridine afford the 3-nitro derivatives in 90% and 66% yield, respectively.239 For the preparation of 4-nitro-pyridine it is better to start from pyridine 1-oxide 240-242... 

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. ... 

Nitration of 2,6-dichloropyridine-l-oxide (IX-188) gives 2,6-dichloro-4-nitro-pyridine-1-oxide (IX-189), which, on catalytic reduction using Raney nickel as the catalyst, gives 4-amino-2,6-dichloropyridine (IX-190). From the amino compound, the 2,6-dichloro-4-nitraminopyridine (IX-191) is readily formed and rearranges to IX-192. Catalytic reduction of IX-192 gives an almost quantitative yield of 2,6-dichloro-3,4-diaminopyridine (IX-193). ... 

A mixture of 3-hydroxy-6-nitro-2-picoline, dimethylamine, and 30% formalin gives 2-[2-(dimethylamino)ethyl] -3-hydroxy-6-nitropyridine. 2-Amino-methyl-5 hydroxy-6-nitropyridine is prepared similarly from 3-hydroxy-2-nitro-pyridine. ... 

Alkoxy-3-halopyridine-l-ox-ide, N-deoxygenated, 725 4-Alkoxy-3-halopyridine-l-ox-ides, from 3-halo-4-nitro-pyridine-l-oxides, 688 4-Alkoxy-3-halopyridines, from... 

Olah s original preparative nitrations were carried out with mixtures of the aromatic compound and nitronium salt alone or in ether, and later with sulpholan as the solvent. High yields of nitro-compounds were obtained from a wide range of aromatic compounds, and the anhydrous conditions have obvious advantages when functional groups such as cyano, alkoxycarbonyl, or halogenocarbonyl are present. The presence of basic fimctions raises difficulties with pyridine no C-nitration occurs, i-nitropyridinium being formed. ... 

It has been mentioned ( 4.4.2) that nitronium tetraffuoroborate reaets with pyridine to give i-nitropyridinium tetraffuoroborate. This compound and several of its derivatives have been used to effect what is called the transfer nitration ofbenzeneandtoluene. i-Nitropyridinium tetraffuoroborate is only sparingly soluble in acetonitrile, but its homologues are quite soluble and ean be used without isolation from the solution in which they are prepared. i-Nitropyridinium tetra-fluoroborate did nitrate toluene in boiling aeetonitrile slowly, but not at 25 In eontrast, i-nitro-2-pieolinium tetraffuoroborate readily... 

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