Nitriles from hydroxylamine

Microwave irradiation of amidoximes in the presence of an aldehydes under solvent-free conditions has been reported to give fully conjugated 1,2,4-oxadiazoles directly, a process that is notable because the amidoximes can be prepared in the same reaction vessel from a nitrile and hydroxylamine (Scheme 33) <2006TL2965>. 

The adducts derived from aldoximes and carbodiimides are not stable. They undergo dissociation to give nitriles 472. This reaction is a useful synthetic route to produce nitriles from aldehydes and hydroxylamine in the presence of DCC and cupric salts in one step. The reaction of of the oximes with carbodiimides is best conducted in a two phase system (methylenechloride/water) using triethylamine, and the yields are almost quantitative." ... 

A new method, employing 0-(2-aminobenzoyl)hydroxylamine and BF3 Et20, has been discovered for the synthesis of nitriles from aldehydes yields are 78-94 % (Eq. 90) [147]. 

Related metallacycles have also been prepared from diamines at Pt11 centers137 and from hydrazines which give the amidrazone chelates (14) (M = Fe,138 Ru,139 Os,140 W141). In addition O-containing metallacycles, (15) (M = MoIV142 WVI143), have been reported from /V-addilions, to nitriles, of hydroxylamines. The O-additions of these ambidentate nucleophiles were discussed above. 

Rearrangement of amide oximes (available from nitriles and hydroxylamine) to monosubstituted ureas by treatment with benzenesulfonyl chloride and water ... 

Hydroxylamine hydrochloride-sodium formate Nitriles from aldehydes... 

Since it has been reported that amidoxime compound is synthesized from nitrile and hydroxylamine ) and that heavy metal ions are coordinated with amidoxime group ), the metal chelating resin is synthesized ) ) and applied to separate and to collect metal ions from diluted solutions ). Egawa et al. reported that metal chelating amidoxime resin which is synthesized from acrylonitrile-divinylbenzene... 

Addition of iV-nucleophiles converts nitriles into amidoximes, amidines, amidrazones, etc., which are valuable intermediates, especially for the preparation of heterocycles. For example amidoxime prepared from p-hydroxybenzo[ C]nitrile and hydroxylamine, reacted with nicotinoyl chloride to give 3,5-disubstituted l,2,4-[3- C]oxadiazole the... 

Some 5-nitro-2-thienyl-pyrazoles have been prepared for a study of their antimicrobial activity. The oximes of thienyl- and selenienyl-carboxamides, prepared from the nitriles and hydroxylamine, give 1,2,4-oxadiazoles by reaction with triethyl orthoformate in BFs etherate. Starting from cyano-thiophens and cyano-selenophens, thienyl- and selenienyl-triazoles and tetrazines were prepared. From the jS-diketone (184) the triheterocyclic (185) was obtained... 

Aldehydes of different types can be conveniently prepared from the next lower halides through carbinols which are split by dia-zotized sulfanilic acid Aliphatic aldehydes in particular can be easily obtained from carboxylic acids through N-acylethylenimi-es Aldehydes, in turn, can be converted directly into nitriles with hydroxylamine hydrochloride Ketones can be efficiently prepared from ethylene derivatives via boranes and, in high purity, from labile alcohols by oxidation in an aq.-ethereal two-phase medium Heating aliphatic acids with reduced iron powder proved to be an excellent method for the prepn. of sym. straight-chain ketones /5-Aminoketones unobtainable by Mannich reaction may be prepared via halogenomagnesium enolates... 

Other Applications. Hydroxylamine-O-sulfonic acid [2950-43-8] h.2is many applications in the area of organic synthesis. The use of this material for organic transformations has been thoroughly reviewed (125,126). The preparation of the acid involves the reaction of hydroxjlamine [5470-11-1] with oleum in the presence of ammonium sulfate [7783-20-2] (127). The acid has found appHcation in the preparation of hydra2ines from amines, aUphatic amines from activated methylene compounds, aromatic amines from activated aromatic compounds, amides from esters, and oximes. It is also an important reagent in reductive deamination and specialty nitrile production. 

In theory, three isoxazolines are capable of existence 2-isoxazoline (2), 3-isoxazoline and 4-isoxazoline. The position of the double bond may also be designated by the use of the prefix A with an appropriate numerical superscript. Of these only the 2-isoxazolines have been investigated in any detail. The preparation of the first isoxazoline, 3,5-diphenyl-2-isoxazoline, from the reaction of )3-chloro-)3-phenylpropiophenone with hydroxylamine was reported in 1895 (1895CB957). Two major syntheses of 2-isoxazolines are the cycloaddition of nitrile A-oxides to alkenes and the reaction of a,/3-unsaturated ketones with hydroxylamine. Since 2-isoxazolines are readily oxidized to isoxazoles and possess some of the unique properties of isoxazoles, they also serve as key intermediates for the synthesis of other heterocycles and natural products. 

A -Isoxazolines are readily available from the 1,3-dipolar cycloaddition of nitrile -oxides with alkenes and from the condensation reaction of ehones with hydroxylamine. Therefore, methods of conversion of -isoxazolines into isoxazoles are of particular interest and of synthetic importance. 

Both 4,5-dimethylisoxazole and 3,4-dimethylisoxazole are formed on treatment of the sodium derivative of a-methylacetaldehyde with hydroxylamine hydrochloride. The two isomers can be separated by fractional distillation <62HC(17)1, p. 54). 4,5-Dialkylisoxazole or 3,4-dialkylisoxazole can be obtained as the sole reaction product from an appropriate nitrile iV-oxide and an appropriate vinyl acetate. 

The two major methods of preparation are the cycloaddition of nitrile oxides to alkenes and the reaction of a,/3-unsaturated ketones with hydroxylamines. Additional methods include reaction of /3-haloketones and hydroxylamine, the reaction of ylides with nitrile oxides by activation of alkyl nitro compounds from isoxazoline AT-oxides (methoxides, etc.) and miscellaneous syntheses (62HC(i7)i). 

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 —... 

Acetylation.—Gitronellal may be quantitatively estimated by the ordinary acetylation process i when the aldehyde is quantitatively converted into isopulegyl acetate, which is then determined by saponification with potash in the ordinary way. Dupont and Labaume have attempted to base a method for the separation of geraniol from citronellal in citron-ella oils on the fact that the citronellal oxime formed by shaking with hydroxylamine solution at the ordinary temperature is not converted into an ester by subsequent acetylation, but into the nitrile of citronellic acid which is stable towards" alkali during the saponification process. 

Aldoximes are prepared from aldehydes and hydroxylamine by condensation reaction, and the dehydration reaction of aldoxime is one of the most important methods of nitrile synthesis in organic chemistry." We speculated that it would become one of the most important examples in Green Chemistry if the dehydration reaction could be realized by an enzymatic method, and started studies on a new enzyme, aldoxime dehydratase, and its use in enzymatic nitrile synthesis. Furthermore, we clarified the relationship between aldoxime dehydratase and nitrile-degrading enzymes in the genome of the microorganisms and the physiological role of the enzyme. 

On the other hand, 3-phenylpropionitrile was synthesized from Z-3-phenyl-propionaldoxime (0.75 M) in a quantitative yield (98gP ) by the use of cells of E. coli JM 109/pOxD-9OF, a transformant harboring a gene for a new enzyme, phenylacetaldoxime dehydratase, from Bacillus sp. strain OxB-1. Other arylalkyl- and alkyl-nitriles were also synthesized in high yields from the corresponding aldoximes. Moreover, 3-phenylpropionitrile was successfully synthesized by the recombinant cells in 70 and 100% yields from 0.1 M unpurified P/Z-3-phenylpropionaldoxime, which is spontaneously formed from 3-phenylpropionaldehyde and hydroxylamine in a butyl acetate/water biphasic system and aqueous phase, respectively. 

Reaction of 3-formyM/7-pyrido[ 1,2- ]pyrimidin-l-ones with hydroxylamine O-sulfonic acid at 5 °C, then 50 °C yielded 3-nitriles <2003T4113>. Treatment of 2-hydroxy-3-(dimethylamono)methyF4//-pyrido[l,2- ]pyrimidin-4-one with Mel, then with KCN gave the 3-cyanomethyl derivative <2004MI215>. A condensation product was obtained from 5-amino-l-ethyl-6-hydroxy-l,3-dihydrobenzimidazol-2-one and 3-lbrmyl-2-hydroxyA//-pyndo[ 1,2- ]pynmidin-l-one <2002W002/38549>. l-(2-Aminopyrimidin-4-yl)-8-phenyl-l,2,3,4-tetrahydro-6//-pyrido[l,2- ]pyrimidin-6-ones were prepared from l-(2-methylthiopyrimidin l-yl)-8-phenyl-l,2,3,4-tetrahydro-6//-pyrido[l,2- ]pyrimidin-6-one by treatment with MCPBA, and then with aralkylamines <2005W005/070932>. 

Intramolecular nitrile oxide-alkene cycloadditions also provide efficient access to six-membered rings such as cyclohexanes or decalins that are heavily adorned with functional groups and side chains. For example, this strategy was used to prepare racemic hemaldulcin (213), which is a 3,6-disubstituted cyclohexenone found in a Mexican plant that possesses a strong sweet taste. Starting from (2Z,6E)-famesal (209) (328) (Scheme 6.88), the aldehyde was treated with hydroxylamine... 

Ammonia or an amine can also be introduced between a terminal aldehyde or a ketone and a suitably placed double or triple bond, although the method is of limited use. A poor yield of 4-picoline is obtained when the aldehyde (262) is treated with ammonia or an ammonium salt (49JCS1430) and dihydroquinolines from the phenylethyl ketones (263) and hydroxylamine (76MI20800). More commonly, cyclization occurs by insertion of ammonia, amines or hydroxylamine between two triple or double bonds in the former case, pyrid-4-ones (264) are obtained (54BSF734) in the latter, a piperid-4-one (265) results (1897CB231). Amines have also been used to give N -substituted piperid-4-ones (70OMR(2)197>. In these cases a double 1,4-addition must be involved in the cyclization of the unsaturated nitrile... 

The nitrile can be prepared from citral by reaction with hydroxylamine and subsequent dehydration with acetic anhydride. 

The product (15-2) from aldol condensation of meto-nitrobenzaldehyde with the dimethyl acetal from ethyl 4-formylacetoacetate (15-1) provides the starting material for a dihydropyridine in which one of the methyl groups is replaced by a nitrile. Reaction of (15-2) with the eneamine from isopropyl acetoacetate gives the corresponding dihydropyridine hydrolysis of the acetal function with aqueous acid affords the aldehyde (15-3). That function is then converted to its oxime (15-4) by reaction with hydroxylamine. Treatment of that intermediate with hot acetic acid leads the oxime to dehydrate to a nitrile. There is this obtained nilvadipine (15-5) [16]. 

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