Oxime groups

In similar hydrolytic processes in basic solution, the oxime group has been shown to afford general base catalysis.Both syn- (265) and anti-(264) oximes show enhanced hydrolysis rates in hydroxide solution, but the syn isomer is faster. The anti isomer hydrolysis is 10 times faster than 

Oximes are useful in preparing isoxazolines and isoxazoles. Since some ring closures to produce these heterocycles may involve oxime anchi-merism, Scott and MacConaill studied the reaction with a number of Mannich base oxime methiodides. They found that the oximate anion was a powerful nucleophile and that displacement of trimethylamine, as in (266), occurred stereospecifically. The oxime of structure (267) undergoes elimination rather than cyclization. 

Oxonium Ions in Organic Chemistry, Verlag Chemie-Academic Press, Wein-heim/Bergstr. (1971) C. U. Pittman, Jr., S. P. McManus, and J. W. Larsen, Chem. Rev., 72, 357(1972). 

Bender, Mechanisms of Homogeneous Catalysis from Protons to Proteins, John Wiley Sons, Inc. (Interscience Division), New York (1971), Chap. 4 W. P. Jencks, Catalysis in Chemistry and Enzymology, McGraw-Hill Book Company, New York (1969), Chap. 3. 

Jencks, I. Givot, and A. Satterthwait, unpublished results quoted by Jencks in Ref. 83, p. 170 W. P. Jencks, personal communication. 

---

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. 

If the carbonyl grou]) in the 3-position of N-methylisatin or tlii-ana])hthencquinone is blocked by formation of an oxime (cf. 112), A -methylation of the oxime group occurs instead of ring expansion on reaction with diazomethane. In methanol, thianaphthenequinone oxime iV-mcthyl ether (113) then undergoes ring opening catalyzed by diazoniethane (113 114). 

Since one proton separation will hardly occur at pH 2.2, extraction ratios of Fe " with compounds 1-7 are quite low. Yet compound 8, which carries oxime groups, was able to extract a considerable amount of Fe- at pH 2.2. 

Deligoz and Yilmaz [52] reported that the selective liquid-liquid extraction of various alkali and transition metal cations from the aqueous phase to the organic phase as carried out by using p-tert-h iy calix[4]arene (1), p-tert-b x. y calix[6]arene (2), tetra-ethyl-p-tm-butylcalix[4]arene-tetra-acetate (3), tetra-methyl-p-/< /-/-butyl calix[4]arene-tetraketone (4), calix[n]arenes ( = 4 and 6) bearing oxime groups on the lower rim (5 and 6) and a polymeric calix(4]arene (8). It was found that compounds 5 and 6 showed selectivity towards Ag, Hg, Hg, Cu, and Cr and the order of the ex-tractability was Hg > Hg > Ag > Cu > Cr. The polymeric calix[4]arene (8) was selective for Ag, Hg, and Hg , unlike its monomeric analog. 

When modified fibres of type 5 are treated with hydroxylamine, oxime groups are also easily formed. The interaction with a protein affords a sandwich polymer22. Fibres modified in this way have enhances dyeability. When copolymer fibres are treated with diamine solutions or in acid medium with Fe+3 salts, intermolecular chemical bonds are formed, which results in a considerable increase of the temperature of zero strength and of the heat resistance of fibres. These conversions are shown in Scheme 2. 

For oximes, the relationship between the sweet and bitter tastes and their structures was systematically studied by Acton and coworkers. By modifying the terpene moiety and keeping the oxime group intact, it was... 

Photolysis of the oxime group in the pyrazole miticide fenpyroximate resulted in the formation of two principal transformation products the nitrile via an elimination reaction and the aldehyde by hydrolysis (Swanson et al. 1995). 

Pyrimidine oximes 286, 287, and 289 are oxidized with nitric acid to furoxanes 288 <2005RJC457, 2004CHE361> in the case of oximes 287 and 289, the reaction is accompanied by the hydrolysis of the oxime group in the 4-position of the starting pyrimidine (Scheme 74) <2005RJC457>. 

Tautomerism exists in the case of o- and p-nitrosophenols and naphthols which exist mainly as the quinone oximes, and which also give high field shifts. The values for the oxime groups in the 1,2-naphthoquinones, for example, were 229 and 265 ppm for the 1-oxime and the 2-oxime respectively. 

Oximes can act both as anionic and neutral ligands. Complexes of Box (134), DBox (135), Fox (136), BMox (137) and DAMox (138) with lanthanide chlorides have been reported. These oximes act as bidentate ligands coordinating through the oxygen of the C=0 or the C-O—H group and the oxime group. 

Sunamoto et al. 94) have studied the reaction of (14) with 2,4-dinitro-phenyl sulfate in aqueous organic solvent with 0.1 A sodiiun hydroxide. The rate of esterolysis by (14) was greater than the rate of the reaction catalyzed by -cyclodextrin. Better binding by the paracyclophane cavity and the greater nucleophilicity of the oxime group as compared to the secondary hydroxyl group of jS-cycdextrin were cited to explain the difference in catalytic efficiency. 

Marchand and co-workers ° synthesis of 5,5,9,9-tetranitropentacyclo[5.3.0.0 .0 °.0 ] decane (52) reqnired the dioxime of pentacyclo[5.3.0.0 .0 °.0 ]decane-5,9-dione (49) for the incorporation of the four nitro groups. Synthesis of the diketone precursor (48) was achieved in only five steps from cyclopentanone. Thus, acetal protection of cyclopentanone with ethylene glycol, followed by a-bromination, and dehydrobromination with sodium in methanol, yielded the reactive intermediate (45), which underwent a spontaneous Diels-Alder cycloaddition to give (46). Selective acetal deprotection of (46) was followed by a photo-initiated intramolecular cyclization and final acetal deprotection with aqueous mineral acid to give the diketone (48). Derivatization of the diketone (48) to the corresponding dioxime (49) was followed by conversion of the oxime groups to gem-dinitro functionality using standard literature procedures. 

Triketone (57), a key intermediate in the synthesis of 4,4,7,7,11,11-hexanitropentacyclo [6.3.0.0 .0 °.0 ]undecane (61) (Zlj-hexanitrotrishomocubane), has been synthesized independently by both Marchand and co-workers, and Fessner and Prinzach. Marchand and co-workers prepared the trioxime (58) from the corresponding triketone (57). Oxidation of (58) with peroxytrifluoroacetic acid in acetonitrile provides a direct route to the trinitro derivative (59) in 35 % yield, this yield reflecting an efficiency of 70 % for the oxidation of each oxime group. Subsequent oxidative nitration of (59) with sodium nitrite and potassium ferricyanide in aqueous sodium hydroxide yields the target T>3-hexanitrotrishomocubane (61). 

Axenrod and co-workers reported a synthesis of TNAZ (18) starting from 3-amino-l,2-propanediol (28). Treatment of (28) with two equivalents of p-toluenesulfonyl chloride in the presence of pyridine yields the ditosylate (29), which on further protection as a TBS derivative, followed by treatment with lithium hydride in THF, induces ring closure to the azetidine (31) in excellent yield. Removal of the TBS protecting group from (31) with acetic acid at elevated temperature is followed by oxidation of the alcohol (32) to the ketone (33). Treatment of the ketone (33) with hydroxylamine hydrochloride in aqueous sodium acetate yields the oxime (34). The synthesis of TNAZ (18) is completed on treatment of the oxime (34) with pure nitric acid in methylene chloride, a reaction leading to oxidation-nitration of the oxime group to em-dinitro functionality and nitrolysis of the A-tosyl bond. This synthesis provides TNAZ in yields of 17-21 % over the seven steps. 

Electrochemical oxidation of phenol substituted by a side chain containing an oxime group afforded a spiro-isoxazole in a quantitative yield (equation 18) . 

An oxime derivative of indirubin (a natural bis-indole alkaloid used in traditional Chinese medicine to treat chronic myelocytic leukemia), indirubin-3 -monoxime (37), was found to be a potent inhibitor of cyclin-dependent kinases (CDKs), and of the proliferation of myeloid leukemia cells via inhibition of a tyrosine kinase . The 3D structure of the complex of 37 with CDK revealed that the oxime function is intact, and that it occupies the ATP-ribose site of the CDK-ATP structure. While the specific role of the oxime group in the biological activity of 37 is not clear, it was proposed that its reactivity may be utilized for further drug design... 

---