4-Chloroacetophenone oxime

Chloroacetophenone oxime was prepared by a modification of the method described by Shriner, Puson, and Curtin. A mixture of 100 g-. (0.65 mole) of reagent-grade 4-chloroacetophenone, 300 ml. of water, 200 ml. of aqueous 10% sodium hydroxide, 50 g. (0.72 mole) of hydroxyl-amine hydrochloride, and 500 ml. of ethanol is heated at reflux in a 2-1. round-bottomed flask for 2 hours. The crystals that separate on cooling in an ice bath are recovered by filtration and air dried. The product is added to approximately 11. of hexane, and the mixture is... 

Chlorophenyl)-5-(4-methoxyphenyl)isoxazole has also been prepared from the dilithio derivative of 4-chloroacetophenone oxime by two other methods (a) reaction with anisonitrile (4-methoxybenzoni-trile) followed by acid-catalyzed cyclization and (b) condensation of anisolyl chloride (4-methoxybenzoyl chloride) followed by acid-cataljrzed cyclization. ... 

A. (o-Bromo-p-chloroacetophenone oxime. A 500-mL, four-necked, round-bottomed flask equipped with a dropping funnel (closed with a giass stopper), mechanicai stirrer, drying tube (calcium chioride, CaCij), and a thermometer is charged with p-chloroacetophenone (38.6 g, 0.25 moi), glacial acetic add (220 mL) and aqueous hydrobromic acid (HBr) [1 mL, 48 % (w/w). Note 1]. The flask is immersed in a water bath (15°C, Note 2) and bromine (40.0 g, 0.25 mol) is added from the dropping funnei at such a... 

Drying lo-bromo-p-chloroacetophenone oxime was carried out in the dark since otherwise this material turns pink in light. Wrapping the flask with )luminum foil provides adequate light protection for this purpose. 

Azetes are known to undergo [2+2] cycloreversion to provide acetylene and hydrogen cyanide <1996JPC1569>. The reaction of chloroacetophenone oxime 659 with LDA yielded another oxime 660 (Equation 252). The formation of this product has been explained by [2+2] cycloreversion of the azetes 661 formed in the reaction (Scheme 84) <2003AGE5613>. 

The furooxazines obtained from the cycloaddition of a-nitrosostyrene, generated in situ from chloroacetophenone oxime, to 2,5-dimethylfuran react further with nitrosostyrene, or with other nitrosoalkenes, to yield the tricyclic nitrones (77) (Scheme 5) <90JCS(Pi)i497>. 

Sodium hydride (11 mmol) was added to 50 ml DMF, 4 portions of chloroacetophenone oxime (1.7 g) added, and the mixture stirred at ambient temperature 30 minutes. Thereafter, the product from Step 3 (10 mmol) dissolved in 10 ml DMF was added dropwise. The mixture stirred at ambient temperature 2 hours, poured into cold 2 M HCl, and the product extracted with methyl t-butyl ether. The combined organic phases were washed with water, dried, concentrated, purified by chromatography on silica gel using methyl t-butyl ether/n-hexane, and the product isolated in 80% as a colorless oil. HNMR data supplied. 

I mol. chloroacetophenone reacts with 3 mols. hydroxylamine hydrochloride in dilute methanol solution at ordinary temperatures, with formation of a-chloroacetophenone oxime, of the formula ... 

M-Bromo-p-chloroacetophenone oxime Ethanone, 2-bromo-1-(4-chlorophenyl)-oxime (12) (136978-96-6)... 

The enol ether is dissolved in 25 mL of rm-butyl methyl ether/mmol of alkene, and treated with 0.5-1.0 equiv of a-chloroacetophenone oxime. Then 6-10 equiv of freshly ground anhyd Na,C03 are added and the mixture is stirred for 6-10d at 20°C. The progress of the reaction is monitored by TLC. Filtration through a short pad of Celite followed by evaporation provides the crude 1,2-oxazines which are purified by column chromatography (aluminum oxide III, neutral, pentane/fert-butyl methyl ether 9 1) to furnish the pure cycloadducts. 

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