Oximes acetic anhydride

From aldehydes by conversion into the oximes, followed by removal of the elements of water by the action of acetic anhydride, for example ... 

The creation of the N—N bond as the last step of the ring synthesis is common in indazoles and very rare in pyrazoles. In indazoles this method is well known (type B synthesis (67HC(22)l), for example, the dehydration of oximes (570) with acetic anhydride yields 1-acetylindazoles (571), and in basic medium the indazole 1-oxides (573) are formed from the nitro derivatives (572). 

The electrochemical reduction of 3-nitrophthalic acid at controlled potentials gave 2,1-benzisoxazole-3-carboxylic acid. Cyclization is presumed to proceed via an intermediate oxime (67AHC(8)277). Treating 5-iodoanthranilic acid with acetic anhydride gave 3-acetoxy-5-iodo-2,l-benzisoxazole (596) (65JMC550). 

This method is an adaptation of that of Dengel. -Methoxy-phenylacetonitrile can also be prepared by the metathetical reaction of anisyl chloride with alkali cyanides in a variety of aqueous solvent mixtures by the nitration of phenylaceto-nitrile, followed by reduction, diazotization, hydrolysis, and methylation 1 by the reduction of ct-benzoxy- -methoxy-phenylacetonitrile (prepared from anisaldehyde, sodium cyanide, and benzoyl chloride) and by the reaction of acetic anhydride with the oxime of -methoxyphenylpyruvic acid. ... 

Two different sets of experimental conditions have been used. Buu-Hoi et al. and Hansen have employed the method introduced by Papa et using Raney nickel alloy directly for the desulfurization in an alkaline medium. Under these conditions most functional groups are removed and this method is most convenient for the preparation of aliphatic acids. The other method uses Raney nickel catalysts of different reactivity in various solvents such as aqueous ammonia, alcohol, ether, or acetone. The solvent and activity of the catalyst can have an appreciable influence on yields and types of compounds formed, but have not yet been investigated in detail. In acetic anhydride, for instance, desulfurization of thiophenes does not occur and these reaction conditions have been employed for reductive acetylation of nitrothiophenes. Even under the mildest conditions, all double bonds are hydrogenated and all halogens removed. Nitro and oxime groups are reduced to amines. 

Quinazoline 3-oxides were first prepared by Awers and von Meyen-burg in 1891 by the dehydration of o-acylamino benzophenone oximes with acetic acid-acetic anhydride and were assigned the in-dazole structure (33). This was then modified by Bischler to the... 

Further evidence of the difference between rhodinol and citronellol is forthcoming, in that the former yields on oxidation an aldehyde, rhodinal, whose oxime does not yield citronellic acid nitrile when treated with acetic anhydride, nor citronellic acid when the nitrile is treated with alkalis, wheras citronellal, the aldehyde of citronellol, does yield the nitrile and citronellic acid. 

The oxime of perillic aldehyde melts at 102°, and when heated with acetic anhydride in presence of sodium acetate, is converted into the nitrile of perillic acid, a liquid having the following characters —... 

The Oximation process depends on the fact that citronellal oxime, produced by shaking in the cold with a solution of hydroxylamine, is converted on heating with acetic anhydride into a nitrile which is not affected by saponification with alcoholic potash. The difference between the molecular weight of the nitrile formed and that of citronellal is so small as to be negligible, and the calculation of the percentage of geraniol from the saponification value is made by the usual formula. The method of procedure is as follows —... 

Conversion of the aldehyde into a nitrile is accomplished by treatment of an aldose with hydroxvlamine to give an oxime (Section 19.8), followed by dehydration of the oxJme with acetic anhydride. The Wohl degradation does not give particularly high yields of chain-shortened aldoses, but the reaction is general for all aldopentoses and aldohexoses. For example, D-galactose is converted by Wohl degradation into n-lyxose. 

Treatment of the tetralone oxime 2166 with iron powder in DMF in the presence of Me3SiCl 14 and a mixture of acetic anhydride and formic acid gives the N-for-myl amine 2167 in high yield [79]. co-Unsaturated alkoxyalkylazides such as 2168... 

The scheme required to prepare the potent tri-fluoro corticoid cormethasone acetate (292) illustrates the synthetic complexities involved in some of this work. Sequential acetylation of the pregnenolone derivative 278 with first acetic anhydride in pyridine and then acetic anhydride in the presence of tosic acid affords diacetate 279. Reaction of that intermediate with nitrosyl fluoride results initially in addition of the reagent to the 5,6-olefin moiety to afford the fluoro oxime reaction with a second mole of reagent at nitrogen gives the nitroimine derivative 280 passage over alumina serves to hydrolyze the imine function to the corresponding 6-ketone (281). 

An exothermic reaction, sufficiently violent to expel the flask contents, occurs after an induction period of 15-30 s when acetic anhydride is added to a solution of the nitroso compound in acetic acid. 4,4/-Azobis(A,A-dimethylaniline), isolated from the reaction tar, may have been formed in a redox reaction, possibly involving an oxime derived from the nitroso compound. 

Furazan compound 278 was obtained as a by-product from cholestan-3-one oxime 277 by prolonged heating in an acetic anhydride-pyridine mixture followed by treating with acetyl nitrate prepared from acetic anhydride and nitric acid (Equation 53) <1997T16161>. 

On treatment with dimethyl sulfoxide-acetic anhydride followed by sequential oximation, reduction, detritylation, and acid hydrolysis, a tetra-(6-0-trityl)-cyclohexaamylose was reported to afford 2-amino-2-deoxy-D-glucose, in addition to D-glucose, indicating459 that... 

In the process described in the literature, the oxime, sodium acetate, and acetic anhydride are allowed to react without dilution, a condition which frequently leads to an uncontrollably violent reaction. 

The above method for preparing glucose oxime is the modification of that of Jacobi1 developed by Wohl,2 who first converted the oxime into the pentaacetyl glucononitrile by means of acetic anhydride. The latter reaction was later employed for the same purpose by Zemplen and Kiss.3... 

By Dehydration of a-Diketone Hydrazone Oximes Another general method of synthesis of 2i/-triazoles involves intramolecular elimination of water from adjacent hydrazone and oxime functions (Scheme 32). The usual reagent is acetic anhydride, but others, including phosphorus pentachloride and urea, have been used. 

If the hydrazone is unsubstituted, dehydration with acetic anhydride gives a 2-acetyltriazole, which is readily converted into an unsubstituted triazole.Oxidation of a-diketone hydrazone oximes with cupric sulfate in aqueous pyridine leads to the formation of 2.ff-triazole-1-oxides. ... 

Selective reduction of the nitrile group in 87% yield without the reduction of the carbonyl was achieved by stannous chloride [1153]. Oximes of keto nitriles are reduced preferentially at the oximino group by catalytic hydrogenation in acetic anhydride over 5% platinum on carbon (yield 85%)... 

Wohl prepared the acylated nitriles of the aldonic acids by heating the aldose oximes with a mixture of sodium acetate and acetic anhydride. With careful control of the reaction, this method may be used for preparative work with fairly good results. 

Afterward, Behrend found that the nitrile is also produced when o-glucose oxime is treated with pyridine and acetic anhydride, and this method has been extended to the preparation of other nitriles of aldonic acids. ... 

In the case of the oximes of the aldose sugars, the situation is more complicated because of the possibility of both open-chain and cyclic structures. That aldose oximes can react in the open-chain form follows from the formation of the nitriles and from the isolation of acylated open-chain aldose oximes as secondary products in preparation of nitriles. For example, Wolfrom and Thompson, by the action of sodium acetate-acetic anhydride on n-glucose oxime, not only obtained pentaacetyl-D-glucononitrile, in 40% yield, but also isolated a small amount of hexaacetyl-oWeAydo-D-glucose oxime (V) identical with that prepared by mild acetylation of pentaacetyl-aWe%do-D-glucose oxime (IV) whose structure was assured by its formation from pentaacetyl-aldehydo-D-glucoae (III). 

This hexaacetyl-aWe%do-D-glucose oxime was easily transformed into the nitrile by heating at 135-140 , or by treatment with sodium acetate-acetic anhydride, and Wolfrom and Thompson considered the open-chain oxime and its acetylated derivative to be an intermediate in the production of the nitrile. We have no proof of the original structure of the oxime. Under the conditions of temperature employed, even a syn oxime can be transformed into the nitrile. If we accept the assumption that the isolated open-chain oxime is the only intermediate, its... 

Acetylated aldose oximes with a ring structure have also been obtained during the preparation of the nitriles, both with sodium acetate-acetic anhydride and with pyridine-acetic anhydride. Thus it appears that under these conditions at least a certain amount of the oxime is present in the ring form. 

A cyclic hexaacetyl oxime (XII) was also isolated by mild acetylation of D-galactose oxime and by treatment with sodium acetate and acetic anhydride. A cyclic aldoxime acetate (XIII) was also obtained by Voto6ek from D-fucose oxime, and by Restelli de Labriola and Deulofeu ... 

Preparation of nitrile acetates from oximes with sodium acetate and acetic anhydride. Pentaacetyl-v-glucononitrile. If only the nitrile is needed, isolation of the oxime can be avoided. One hundred grams of anhydijous n-glucose was dissolved in 50 ml. of warm water, and maintaining the temperature at 60°, a solution of 28 g. of hydro-xylamine in 700 ml. of ethanol was added sufficiently slowly that no precipitation took place. After one hour at 65°, the reaction mixture was concentrated under reduced pressure to a thick sirup. The residue was mixed with absolute ethanol, the ethanol evaporated and the operation repeated in order to eliminate all water. One hundred and twenty grams of anhydrous sodium acetate and 700 ml. of acetic anhydride were added to the sirup, and the mixture was slowly and cautiously warmed in a water bath to 95°. It was advisable to agitate the flask continuously and to watch the... 

Preparation of acetylated nitriles from oximes with pyridine-acetic anhydride. Penta-acelyl-n-glucosaminonitrile. One gram of D-glucosamine oxime hydrochloride was treated with 6 ml. of pyridine and 6 ml. of acetic anhydride and kept at 20° until solution had occurred. The solution was then concentrated and the crystalline residue was recrystallized from ethanol yield 1.8 g. (84%), m. p. 126°. 

D-Xylose. Maquenne obtained tetraacetyl-D-xylononitrile in 41% 3deld from the D-xylose employed, by treatment of the oxime with sodium acetate-acetic anhydride. From the nitrile, D-threose diacetamide was obtained in 30 % yield by the action of ammonia and it was hydrolyzed... 

D-Fucose (Rhodeose). Voto6ek obtained tetraacetyl-D-fucononitrile in 25% yield by treating D-fucose oxime with sodium acetate-acetic anhydride. The nitrile, degraded with ammonia and silver oxide, yielded 5-desoxy-D-lyxose diacetamide in 40% yield. The diacetamide compound was hydrolyzed with 5% hydrochloric acid and the 5-desoxy-D-lyxose was obtained in solution and characterized as the p-bromo-phenylosazone. Hydrolysis of the diacetamide compound with 6 N sulfuric acid was realized by Voto6ek and Valentin and the 5-desoxy-D-lyxose was isolated as a sirup. 

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