Aldoximes aliphatic

Nitriles from aldoximes. Aliphatic, aromatic, and olefinic aldoximes (1 mole) are dehydrated by treatment with triethylamine (3 moles), and phosphonitrilic chloride (1 mole) in ether or THF at room temperature for 8 24 hr. yields are in the range... 

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. 

The NHase responsible for aldoxime metabolism from the i -pyridine-3-aldoxime-degrading bacterium, Rhodococcus sp. strain YH3-3, was purified and characterized. Addition of cobalt ion was necessary for the formation of enzyme. The native enzyme had a Mr of 130000 and consisted of two subunits (a-subunit, 27 100 (3-subunit, 34500). The enzyme contained approximately 2 mol cobalt per mol enzyme. The enzyme had a wide substrate specificity it acted on aliphatic saturated and unsaturated as well as aromatic nitriles. The N-terminus of the (3-subunit showed good sequence similarities with those of other NHases. Thus, this NHase is part of the metabolic pathway for aldoximes in microorganisms. 

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

HANSEN, C.H., WITTSTOCK, U., OLSEN, C.E., HICK, A.J., PICKETT, J.A., HALKIER, B.A., Cytochrome P450 CYP79F1 from Arabidopsis catalyzes the conversion of dihomomethionine and trihomomethionine to the corresponding aldoximes in the biosynthesis of aliphatic glucosinolates, J. Biol. Chem., 2001, 276, 11078-11085. 

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],... 

Reactions with several other dinucleophiles have been studied. These include NaOC6H4CHaOH-o, which gives N3P3(OC6H4CH2OH-o) C16-w (n — 2, 3, 4, 6), the latter of which was the precursor of a condensation polymer.131 Salicylic acid in the presence of triethylamine gives (60), which can be sublimed to give (61).132 Aliphatic and aromatic aldoximes can be converted into nitriles by reaction with... 

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. 

If there were ever a simple comparison of enthalpies of formation to be investigated as part of this chapter it would be the oximes of the aliphatic aldoximes, RCH=NOH, as R proceeds through Me, Et, n-Pr,. Ideally, we would have the values for at least R = Me and Et and then employ the universal methylene increment to derive the remaining values by addition of —20.6 kJmoR for gaseous species and a related ca —26.0 kJ moR for... 

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. 

The use of soluble amine bases failed to give products, whereas the heterogeneous conditions KOH/THF proved optimal in promoting aldoxime formation for a broad range of substrates. Optically active nitroalkanes including aromatic (both electron-rich and electron-deficient), heteroaromatic, branched and unbranched aliphatic substrates, as well as substrates that incorporate unprotected alcohol functionalities were successfully reduced. 

The same activity is presented by an iridium complex [Ir(Cp )Cl2]2 that catalyses the Beckmann rearrangement of aromatic, aliphatic and heteroaromatic aldoximes 276 into the corresponding primary amide 277 in good to excellent yields (78-97%) (equation 85). 

Manihot esculenta cytochrome P450 Conversion of vahne and isoleucine to aliphatic aldoximes 103... 

The formation of nitriles from aldoximes was at that time a well-known reaction, at least in its general lines. Gabriel and Meyer found that o-nitrobenzonitrile was obtained by heating o-nitrobenzaldoxime, prepared in an indirect way, with sodium acetate and acetic anhydride Lach prepared benzonitrile in a similar way, and Dollfuss transformed aldoximes of the aliphatic series into nitriles by simple treatment with acetic anhydride. The complicated character of this reaction was demonstrated by the classical work of Beckmann and Hantzsch, who... 

Chloramine-T has also been employed, both as a halogenating reagent and base the reaction proceeds in good yield with aromatic as well as with aliphatic aldoximes (81). The role of chloramine-T probably involves an initial chlorination of the aldoxime to give the hydroximoyl chloride, followed by base-catalyzed hydrogen chloride elimination to afford the nitrile oxide (81). 

It should be noted that aliphatic aldoximes are not oxidized into oxadiazole derivatives. 

Diammonium hexanitratocerate (IV) (CAN) has also been used as an oxidizing agent for aldoximes. This approach is especially useful for the preparation of aliphatic 2-oxo-carbonitrile oxides (99). Another useful reagent for the generation of nitrile oxides from aldoximes is 1-chlorobenzotriazole (100). Due to its reactivity toward both aldoximes and olefins, this reagent can only be used to prepare stable... 

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 yield of nitriles from aliphatic aldoximes under suitable conditions (reaction time 1-5 hr, KOH 0.1-0.3 mol per 1 mol of aldoxime) can attain 92% (76IZV690). At 140°C under the same conditions, benzaldoxime converts to benzamide in 25% yield. 

Since the Pfitzinger reaction requires a large excess of alkali, aliphatic aldehydes, which readily polymerize under these conditions, cannot be used in the reaction. However, it was possible to overcome these difficulties by using the aldoximes. Thus, Pfitzinger heated the isatin 7 with acetaldehyde oxime in the presence of potassium hydroxide in water and obtained 4-quinolinecarboxylic acid together with the oxime of isatinic acid 196 [175],... 

Oxazole IV-oxides cannot be made by oxygenation of oxazoles. The only method of synthesis remains the condensation of monooximes of 1,2-dicarbonyl compounds with aldehydes in the presence of hydrogen chloride (equation 132) (15CB897). The aldehyde may be aromatic or aliphatic (including formaldehyde) and the oxime may be derived from an aromatic diketone or it may be an a-keto aldoxime, leading to a 2,5-disubstituted oxazole IV-oxide. It may also contain an additional carbonyl group as in equation (133). 

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. 

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