2-Acetylpyridine oxime

Pyridine-3-carbohydroxamic acid (nicotinylhydroxamic acid) 2-Acetylpyridine oxime l-(2-Pyridylazo)-2-naphthol (PAN)... 

One-pot transformation of 2-, 3-, and 4-acetylpyridine oximes into pyrroles and N-vinylpyrroles has been implemented [251,252]. Upon heating (KOH/DMSO, 105°C-110°C, 3 h), 2-acetylpyridine oxime and acetylene nnder pressure give a mixture of 2-(2-pyridyl)pyrrole (32%) and its N-vinyl derivative (36%). At 120°C, only 2-(2-pyridyl)-N-vinylpyrrole is formed in 68% yield (Schane 1.65) [251]. 

The product (mp 122-146°C, 33-36 g, 81-88%) can be shown from its 1H NMR spectrum (Note 3) to he a 5 1 mixture of the E- and Z-isomer of 4-acetylpyridine oxime. To obtain pure E-isomer (Note 4), the product is recrystallized twice as follows. The crude product is dissolved in 600 mL of hot water in a 2-L Erlenmeyer flask, the hot solution decanted from any undissolved residue, and the supernatant liquid is allowed to cool slowly to 30°C during 2-3 hr by placing the flask on a cork ring. The precipitate is collected at this temperature by suction filtration. A second crystallization hy the same procedure yields pure E-oxime, which is dried under reduced pressure over Drierite to constant weight. The yield of E-4-acetylpyridine oxime, mp 154-157°C, (Note 5) is 27.1-28.3 g (66-69%). 

The / -toluenesulphonate esters of 2-, 3- and 4-acetylpyridine oximes undergo the Neber reaction 2. 

The analysis of the reasons of lower reactivity of acetylpyridine oximes has shown that, according to the IR and NMR data, the starting oximes are pure -isomers [252], while ketoximes of Z-conflguration are the most reactive in the studied reaction [7]. Since acetylpyridine oximes exist at room temperature as -isomers exclusively, their decreased proneness to formation of pyrroles in the reactions with acetylene becomes apprehensible. With the temperature increase and under the effect of the... 

SCHEME 1.65 Synthesis of 2-pyridylpyrroles from acetylpyridine oximes and acetylene. 

In contrast with the Schiff base salen, salicylaldehyde oxime (79) (salox) complexes of Co have received comparatively little attention, but a series of bis-bidentate divalent complexes of the form iraiis-Co(sa 1 ox)2( D M SO)2 have been reported.343 The heterocyclic bidentate oxime violurate (lH,3H-pyrimidine-2,4,5,6-tetrone 5-oximate, Hvi) (80) and its /V-methyl (mvi) and /V,/V -dimethyl (dmvi) derivatives form high-spin divalent [Co(vi)]+ and Co(vi)2 complexes, whereas [Co(vi)3] is low spin.344 The mixed-ligand Co(dmvi)2(phen) complex is also low spin. The crystal structure of m-Co(pxo)2Br2 (pxo = 2-acetylpyridine-l-oxide oxime) is isostructural with the Ni11 relative.345 The dichloro complex also adopts a cis configuration. The tridentate dioximes 2,6-diformyl-4-methylphenol dioxime and 2,6-diacetyl-4-methylphenol dioxime (Hdampo) form binuclear complexes of the type (81a) and (81b) respectively.346 Cobalt oxide nanoparticles were prepared by... 

Methyl 2-pyridyl ketoxime. A solution of 2-acetylpyridine (3, Acros, 27.2 g, 0.225 mole) and hydroxylamine hydrochloride (18.0 g, 0.259 mole) in 100 mL of pyridine is stirred magnetically and heated to reflux in a 250-mL, round-bottomed flask fitted with a water-cooled reflux condenser for 6 h. After removing the solvent on a rotary evaporator, 400 mL of HzO is added, resulting in precipitation of the oxime in the form of a white precipitate which is isolated by vacuum filtration. The filtrate is extracted three times with 100 mL of ether. The white solid is dissolved in ether and combined with the extracts, and then dried with Na2S04. The solvent is evaporated using a rotary evaporator. The crude product (30.0 g, 97%) is used directly in the next step without further purification. 

Other simple chelate ligands which have been found to give six-coordinate complexes NiX2L2 are 2-acetylpyridine N-oxide oxime,2495 2-acetamidopyridine,2496 pyridine-2-(acetic acid methyl ester)2497 and -substituted 2-aminopyridine N-oxides.2498... 

The chemoenzymatic synthesis of a Ps adrenergic receptor agonist was developed by J.Y.L. Chung and co-workers. The key chiral 3-pyridylethanolamine intermediate was prepared via the Neber rearrangement of the ketoxime tosylate derived from 3-acetylpyridine. The oxime formation and the tosylation were carried out in a one-pot process using pyridine as the solvent. The solution of the ketoxime tosylate in ethanol was then cooled to 10 °C and potassium ethoxide was added. After the TsOK salt was removed from the reaction mixture, HCI gas was bubbled through the solution until the pH reached 2 and the 3-pyridylaminomethyl ketal was isolated as its di-HCI salt. 

Pyridyl)-N-vinylpyrrole (62% yield) and 2-(4-pyridyl)-N-vinylpyrrole (65% yield) have been selectively synthesized from oximes of 3-acetyl- and 4-acetylpyridine, respectively, at 120°C (Scheme 1.65) [252]. 

Acetamidoxime, A-00004 2-Acetyl-l-naphthol Oxime, in A-00026 4-Acetylpyridine 4-ethyl-3-... 

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