Ketoximes aliphatic

The ketoxime derivatives, required as starting materials, can be prepared from the appropriate aromatic, aliphatic or heterocyclic ketone. Aldoximes (where R is H) do not undergo the rearrangement reaction, but rather an elimination of toluenesulfonic acid to yield a nitrile. With ketoxime tosylates a Beckmann rearrangement may be observed as a side-reaction. 

Another arylation reaction which uses arenediazonium salts as reagents and is catalyzed by copper should be discussed in this section on Meerwein reactions. It is the Beech reaction (Scheme 10-49) in which ketoximes such as formaldoxime (10.13, R=H), acetaldoxime (10.13, R=CH3), and other ketoximes with aliphatic residues R are arylated (Beech, 1954). The primary products are arylated oximes (10.14) yielding a-arylated aldehydes (10.15, R=H) or ketones (10.15, R=alkyl). Obviously the C=N group of these oximes reacts like a C = C group in classical Meerwein reactions. It is interesting that the addition of some sodium sulfite is necessary for the Beech reaction (0.1 to 0.2 equivalent of CuS04 and 0.03 equivalent of Na2S03). 

Aliphatic aldoximes and ketoximes undergo palladium-catalyzed O- and N-alkylation by butadiene in reactions that presumably occur via jr-allyl... 

Ketoximes and aldoximes Ketoximes and aldoximes are uniquely substituted C=N systems that react differently with titanocene and zirconocene. Aliphatic and alicyclic O-silylated ketoximes R2C=N OSiMe3 react with complex 1 with elimination of the alkyne and N—O bond cleavage to give imido-silanolates 85 [45],... 

CoH(CN)5] catalyses the hydrogenation of nitro compounds either to amines (aliphatic substrates) or to products of reductive dimerization, i.e. to azo and hydrazo derivatives. Ketoximes and oximes of 2-oxo-adds are hydrogenated to amines. This latter reaction gives a possibihty to directly produce a-amino-acids in the reductive amination of 2-oxo-acids in aqueous ammonia at a temperature of40-50 °C and 70 bar H2 (Scheme 3.1). Yields are usually high (approximately 90%) [18]. 

The Ponzio reaction provides a useful route to gem-dinitro compounds and involves treating oximes with a solution of nitrogen dioxide or its dimer in diethyl ether or a chlorinated solvent. The Ponzio reaction works best for aromatic oximes where the synthesis of many substituted aryldinitromethanes have been reported. Compound (56), an isomer of TNT, is formed from the reaction of dinitrogen tetroxide with the oxime of benzaldehyde (55) followed by mononitration of the aromatic ring with mixed acid. Yields are usually much lower for aliphatic aldoximes and ketoximes. " The parent carbonyl compound of the oxime is usually the major by-product in these reactions. 

Preparative scale reduction of oximes at a mercury or lead cathode in acid solution has been used in the conversion of the carbonyl function to amine. Originally, 30-50% sulphuric acid was used as solvent [195] but ethanol with dilute hydrochloric acid is usually satisfactory. Aliphatic and aromatic oximes give amines in 64-86% yields [196]. Aromatic ketoximes are also reducible in alkaline solution and acetophenone oxime has been converted to 1-phenylethylamine in a tri-potassium orthophosphate solution [197], The reduction of oximes in acid solution is tolerant of many other substituents as indicated by a number of examples [198, 199, 200. Phenylglyoxa monoxime in acid solution is however reduced at both the carbonyl and the oxime centres by sodium amalgam to yield 2-amino-1-phenylethanol [201]... 

The chemical shifts for Z and E forms of 21 aliphatic ketoximes (8-29 in Table 5) were thoroughly investigated They are found in the range 31.4-63.9 ppm. Shieldings for ten aliphatic aldoximes appear between —4.0 and 30.1 ppm (Table 6). 

The term oxime dates to the 19th century, a combination of the words oxygen and imide. Oximes exist as two stereoisomers syn (Z) and anti (E). Aldoximes, except for aromatic aldoximes, exist for the most part as the syn isomer, while ketoximes are obtained as both syn and anti isomers, which can be separated almost completely. Recently, Kolandaivel and Senthilkumar have studied the molecular structure and conformational stability of anti and syn conformers of some aliphatic aldoximes by employing the ab initio and density funetional theory (DFT) methods. 

Boron trifluoride etherate was used in conjunction with the reducing agent borane to rearrange aromatic O-triisopropylsilyl ketoximes to cyclic and acyclic aniline derivatives. The steric hindrance of the substituents on the silicon atom, the size of the aliphatic ring and the presence of alkoxy substituents on the aryl group played important roles in the aniline formation. 

Although true for many oximes of aliphatic and alicyclic ketones, the previous sequence is not absolute and can change depending on the reaction conditions and ketoxime type. Tetrabutylammonium hydroxide, for instance, which catalyzes fairly actively in the synthesis of 4,5,6,7-tetrahydroindole from cyclohexanon oxime and acetylene (79KGS197), turned out to be nearly inert with alkyl aryl ketoximes (78ZOR1733). 

In attempts (76IZV690 80KGS1299 81MI4) to extend the pyrrole synthesis from ketoximes and acetylenes to aldoximes, the oximes of both aliphatic and aromatic aldehydes have been found to readily convert to the corresponding nitriles upon moderate heating (60-140°C) in KOH/DMSO. 

The reaction of isopropyl phenyl ketoxime with acetylene in the KOH/ DMSO system was the first to show that ketoximes having only an aliphatic hydrogen atom in the a-position with respect to the oxime function can serve as the starting material for the synthesis of inaccessible 3//-pyrroles. 

The observed substituent effect on the reaction rate in the oxidation of substituted aliphatic ketoximes by /V-bromosaccharin has been rationalized in terms of a mechanism.126 The oxidation of acetophenones with N-bromophthalimidc exhibited a linear correlation with Brown s a+ with reaction constant p = —0.52. An Exner plot gave an isokinetic temperature p = 263 K. A mechanism consistent with the kinetic data has been proposed.127... 

In contrast to the plethora of reactions between DIB and -containing compounds, BTI has so far limited applications. Among them, its reactivity with oximes is of interest, because several products are formed, depending on the substrate [36]. Aromatic oximes were converted directly into ketones in good yield, whereas aliphatic ketoximes gave isolable intermediates, i.e. 1-nitroso-l-trifluoroacetoxy-alkanes. 

Reeve and Christian compared Raney Ni and Raney Co (W-7 type) for the hydrogenation of six aliphatic and aromatic aldoximes and ketoximes in the presence or absence of ammonia.26 From the results summarized in Table 8.1, it is notable that Raney Co gives high yields of primary amine in ethanol or dioxane without addition of ammonia as seen in the results with butyraldoxime, 2-butanone oxime, and acetophenone oxime. On the other hand, Raney Ni usually requires an ammoniacal solvent for best results, with the exception of acetophenone oxime, which gave high yields of primary amine in the absence of ammonia. 

In principle, the synthesis can be realized as a one-pot process treatment of ketones with hydroxylamine in KOH-DMSO following interaction of the formed ketoximes with acetylene. Various pyrroles with alkyl, cycloalkyl, aryl and hetaryl substituents, as well as pyrroles condensed with aliphatic macrocycles, terpenic and steroid structures, together with their vinyl derivatives now become available. 

Certain substituted ethylenimines are obtained by the action of aliphatic or aromatic Grignard reagents on aryl alkyl ketoximes with subsequent non-acidic decomposition of the intermediate complex (20-60%). ... 

Isomerism of Ketoximes.—In the case of aromatic aldehydes they all yield these stereo-isomeric oximes. With the aromatic ketones the condition is different and some yield stereo-isomers and some do not. With symmetrical aromatic ketones in which the two radicals are alike such as di-phenyl ketone, CgHb—CO—C6H,5 no different space relation of the hydroxyl group is possible as the two forms will be identical. When, however, the ketone is unsymmetrical, i.e.j the two radicals are unlike, as in mixed aromatic-aliphatic ketones such as phenyl methyl ketone, CeHs—CO—CH3, or in unsymmetrical di-aryl ketones such as phenyl tolyl ketone, CeHs—CO—C6H4—CHz then the two stereo forms are possible though both forms are not known in all cases. 

Indirect oxidation using 1 as mediator (I" ) of aliphatic ketoximes affords 2,2-dialkyl-2,5-dihydro-1//-imidazoles, probably through a nitrenium ion or an azirine as intermediate. The intermediate attacks the ketimine to the product [85]. 

Blocked isocyanates are being used in coil coatings, depending on cure temperature, and end uses aliphatic or aromatic isocyanates blocked with 3,5-dimethylpyrazole, methylethyl ketoxime or caprolactam are being employed. 

The reactivity of bis(trifluoroacetoxy)iodobenzene (23) towards oximes is of interest as several products are formed depending on the substrate. 70 a ligand coupling mechanism may be suggested for the reaction of aliphatic ketoximes with bis(trifluoroacetoxy)iodobenzene, which gives fair yields of the stable, intensely blue 1-nitroso-l-trifluoroacetoxyalkanes.271... 

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