3-Picoline-l-oxide

Methylpyridine-l-oxide (3-picoline-l-oxide) may be prepared by a method similar to that employed for pyridine-1-oxide. To a mixture of 600-610 ml. of glacial acetic acid and... 

Phthalaldehyde, 34, 82 Phthalic acid, 32, 67 Phthalic anhydride, 32, 19 Phthalideacetic acid, 34,10 PlITHALIMIDE, N-2-BROMOETHYL-, 32, 18 3-Picoline, 4-nitro-, 1-oxide, 36, 53 3-Picoline-l-oxide, 36, 54... 

Picoline-l-oxide, 36, S4 PiMELIC ACID, 7-0X0-, DIETHYL ESTER,... 

Simultaneous nitration-deoxygenation has also been observed by these workers. For example, pyridine-1-oxide undergoes nitration and deoxygenation with concentrated sulfuric acid and fuming nitric acid at 130 to 165° to give 4-nitropyridine in 71% yield. As additional examples, 3-picoline-l-oxide gives 4-nitro-3-picoline (81%), and 3-bromopyridine-l-oxide affords 3-bromo-4-nitro-pyridine (75%) on treatment with nitric oxide and sulfuric acid at 150 to 200°. 

Contrary to a previous report, the reaction of pyridine-l-oxide with acetic anhydride does not give exclusively 2-pyridone 2-aminopyridine and yV-(2-pyridyl)-2-pyridone (IX-23) are also formed. Similarly, 6-amino-3-picoline and 3-methyl-A -(5-methyl-2-pyridyl)-2-pyridone were isolated in the reaction of 3-picoline-l-oxide with acetic anhydride (see also Chapter IV). 

Studies with 3-substituted pyridines indicate that the product distribution depends on the substituent. When the group in the 3-position is methyl, the two isomeric 2-pyridones are formed in about equal amoxmts. However, when the group is inductively electron withdrawing, the 3-substituted-2-pyridone either predominates or is the only isolated product. 3-Picoline-l-oxide and acetic anhydride give 3-methyl-2-pyridone (35-40%), 5-methyl-2-pyridone (35-40%), and 3-methyl-l-(5-methyl-2-pyridyl)-2-pyridone (4%) after hydrolysis with water. In a later study, much less 3-methyl-2-pyridone was detected. ... 

Methyl-2-pyridone, from 3 -picoline-l-oxide, 718 rate of hydrogen-deuterium... 

Preparation of substituted pyridinecarboxyUc acid 1-oxides by means of H-abstraction is reported by Abramovitch and others. Thus, treatment of the lithium derivative of 4-chloropyridine-l-oxide or 4-chloro-3-methylpyridine-l-oxide with CO2 gave the corresponding 4-chloro- and 4-chloro-5-methylpicolinic acid-1-oxides. Under the same conditions, 4-picoline-l-oxide gave the 2,6-di-carboxylic acid. 

Considerable attention has been devoted to the mechanisms of these reactions during the past decade and with only partial success. It should be emphasized that rearrangement to the nucleus at the 2- or 3-position or to the a-carbons of the side-chain on the 2- or 4-positions are different kinds of reactions. Studies with 0 labeled acetic anhydride show that rearrangement of 2-picoline-l-oxide is intramolecular and that equilibration of the two oxygens from the TV-acetyloxy group takes place. Although this suggests a radical pair ... 

Picoline-l-oxide, 2,6-lutldine-l-oxide, and 4-nitro-2,6-lutidine-l-oxide react with ketene to form the corresponding hydroxymethylpyridine and the corresponding 3-pyridinol in relatively low yields. N-oxides of 3-picoline, 4-nitropyridine, and 4-nitro-2-picoline did not give comparable products when treated with ketene. ... 

Irradiation of pyridine-1-oxides in the gas phase with ultraviolet light can lead to deoxygenation. In benzene the pyridine and some phenol are often formed. Other products include 3-pyridinols, 2-pyridones, and 2-formyl- or acylpyr-2-Picoline-l-oxide gives small amounts of both 2- and 6-methyl-3-pyridinol, in addition to other products. Irradiation of... 

Nitro-3-picoline, from 3-pic-oline-l-oxide, 3 hydrolysis of, 694 4-Nitro-2-picoline-l-oxide, effect of 4-nitro group, 719 reaction with acetic anhydride, 719... 

From 3-picoline A -oxide and phenyl isocyanate the cycloadduct can be isolated Also, nitrile oxides, generated from arylhydroxamoyl chloride and triethylamine, react with phenyl isocyanate to give 2,4-diaryl-l,2,5-oxadiazol-3-ones and nitrile oxide dimers". Mesitonitrile oxide reacts with a l-oxa-3-azonia-butatriene salt 419 (R = 2,4,6-MesPh) by addition across the C=0 bond of the isocyanate to give a 1,2,5-oxadiazole derivative 420" ". ... 

MeOpyNO. 4-ClpyNO, or 4-N02pyN0) and [FeL ](C104)2 (L = 4-picoline. V-oxide. 4-MeOpyNO, 4-ClpyNO, 4-N02pyN0, 4-CNpyNO, or 3-CNpyNO) have been prepared, and have been characterized by magnetic measurements and i.r. and electronic spectroscopy. ... 

Fischer attempted the bromination of apoharmine in dilute sulfuric acid at room temperature and obtained a tetrabromo compound, which he did not characterize further. Treatment of l-benzoyl-2,5-dimethyl-4-azaindole with bromine in acetic acid at 25° gave the 3-bromo-l-benzoyl compound in 60% yield. On oxidation with permanganate it gave the same picolinic acid obtained before. Alkaline hydrolysis gave 3-bromo-2,5-dimethyl-4-azaindole (90%), also obtained by direct bromination of 2,5-dimethyl-4-azaindole in 60 % yield. 

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