Oximes ketones

Acid treatment or thermolysis of aziridinyl phenyl ketone oxime generated a 2-isoxazoline (74JAP(K)74i 17462), while treatment of a diphenylcyclopropene (486) with NOCl generated a 2-isoxazoline in contrast to dialkylcyclopropene (487) which produced addition across the double bond (Scheme 126) (73MI41605). 

The cycloaddition, reduction and oxidation reactions emanating from a,/J-unsatu-rated nitroalkenes provide easy access to a vast array of functionalities that include nitroalkanes, N-substituted hydroxylamines, amines, ketones, oximes, and a-substi-tuted oximes and ketones [73-75], Consequently, there are numerous possibilities of using these in situ generated nitroalkenes for the preparation of valuable building blocks and synthetic precursors. 

The 36d-LAH complex was applied to the reduction of ketone oximes and their O-tetrahydropyranyl and O-methyl derivatives to optically active amines (69). Results for a variety of phenyl alkyl and dialkyl ketones are shown in Table 4. The predominant amines formed all were of the S absolute configuration with optical purities up to 56%. The oxime hydroxy group presumably reacts with the less hindered H2 in the 36d-LAH complex (cf. Scheme 6) to form an oxime complex (45), which probably undergoes infermolecular hydride transfert of H2 from a second molecule of the 36d-LAH complex (Scheme 8). Asymmetric reduction with the ethanol-modified 36d-LAH reagent gave amines of R con-... 

Reduction of Ketone Oximes and O-Tetrahydropyranyl and O-Methyl Derivatives with... 

For the two aldehydes discussed in the previous section (R, R = H R = Me, R = Hep), the reaction is thermoneutral in the gas phase. Thermoneutrality would also be expected for ketones, but which ketone/oxime should be the standard for comparison In the gas phase there are two possibilities acetone/acetone oxime and cyclohexanone/cyclohexanone oxime. The latter pair may be assumed to be essentially strainless, or at least that their strain energies are very much the same. The assumption is borne out by substituting these two pairs into equation 23 (R, R = Me R R = — (CH2)5—) and finding that the enthalpy of reaction is only 1.2 kJ moE, essentially thermoneutral. Comparing the Cg species with the cyclohexyl species (RR = —(CH2)s- R /R = Me/Hex, Et/Pen, Pr/Bu), the enthalpies... 

The reaction of a-halo ketone oximes 204 with isocyanides leads to formation of 5-aminoisoxazole derivatives 205. The reaction involves formation of nitrosoalkenes as intermediates (equation 89) ". ... 

Synthesis of quinolines by nucleophilic substitution of nitrogen atom in oxime derivatives was described by Narasaka and coworkers. /3-Aryl ketone oximes 297 in the presence of trifluoroacetic anhydride and 4-chloranil afforded quinolines 298 in 72-82% yield (equation 128). However, interaction of oxime 299 with 48% HBr at 105 °C proceeded with elimination of hydroxyimino group and gave 2,3-dimethoxynaphtho[l,2-fc]quinolizinium bromide (300) in 45% yield (equation 129). ... 

Amines 297 and/or carboxylic acids 298 may be obtained by amide hydrolysis and the latter compound may be produced from a ketone by a Beckmann rearrangement (equation 103). Therefore, the Beckmann rearrangement of a ketone oxime followed by amide hydrolysis provides a synthetic method to cleave the C—C bond between the carbon... 

Phenethyl ketone oximes have been cyclized by a Beckmann rearrangement to isoquinolines 477 (equation 205), but quinoline derivatives 478 can also be obtained as a result of a formal displacement at the nitrogen atom of the oxime (equation 206). 

The reaction of aliphatic and aromatic ketone oximes 97 with a dialkyl carbonate 98 in the presence of K2CO3 at 180-190 °C yields 3-alkyl-4,5-disubstituted-2(3//)-oxazolones 104 in 22-48% yields. Mechanistically, it is proposed that N-alkylation of the initially formed oxime O-carbonate 99 yields 100, which affords the enamine 101 in the presence of base. A [3,3] sigmatropic rearrangement ensues to produce 102, which then cyclizes to 104. In cases where 97 contains two methylene groups in proximity to the C=N bond, one of which is benzylic, the above reaction sequence is regioselective for the benzylic methylene group (Fig. 5.25 Table 5.6, Fig. 5.26). ... 

Complexes involving oxime ligands display a variety of reactivity modes that lead to unusual types of chemical compounds. As far as the oxime chemistry of platinum is concerned, these complexes are involved in facile deprotonation of the OH group with formation of oximato complexes, reduction of Pt(IV) species, Pt(II)-assisted reactions with coordinated allene," alkylation by ketones, oxime-ligand-supported stabilization of Pt(III)—Pt(III) compounds, oxidative conversion into rare nitrosoalkane platinum(II) species, and coupling with organocyanamides. ... 

Regioselective alkylative opening of a,(1-epoxy ketone oxime [40] and tosylhydra-zones [41] with organocopper reagents is initiated by the generation of unsaturated azo compounds which undergo conjugate addition. 

The oxidation of oximes of oj//-perfluoroaldehydes with fuming nitric acid gives furoxane derivatives, e.g. the preparation of 3,4-bis(8//-hexadecafluoro)-l,2,5-oxadiazole (V-oxide (9).128 The conversion of ketone oximes to nitro compounds is of practical importance. Hexa-fluoroacetone oxime is transformed into l,l,l,3,3,3-hexafluoro-2-nitropropane (10) using dinitrogen pentoxide liberated in situ.249... 

The condensation of methyl perfluorophenyl ketone oxime with acetylene (KOH/DMSO, 100°C, 2 hr, 12 atm) failed to afford the expected pyrrole [90ZOR(ip)]. 

Ketone oximes of the hydronaphthalene series can successfully be transformed into pyrroles. Thus, 4,5-dihydrobenzo[g]indole (38) was prepared in one stage (yield 70%) from a-tetralone oxime (37) and acetylene (Scheme 21) (78ZOR1119). 

Reduction of C=Oy C=N, and C=(V.1 The combination of NaBH4 and ZrCl4 (4 1) reduces ketones, oximes, and nitriles in THF at 25° in 85-96% yields. Reduction of C=N and CseN is slower than that of 0=0. Reduction of oximes affords amines rather than hydroxylamines (obtained with B2H6 as reductant). 

Heating ( )-methyl l-oxide-2-pyridyl ketone oxime (482) in acetic anhydride at temperatures above 100°C initiated an exothermic reaction from which 3-methyl-3a-(3 -methylisoxazolo[4,5-b]pyridin-5 -yl)-3a//-[l,2,5]-oxadiazolo[2,3-a]pyridine (484) was isolated in 18% yield (Scheme 57) <86CPB4984>. If the reaction is carried out at a temperature less than 100°C, only the acetylated oxime (483) is isolated. Heating the (Z)-isomer in acetic anhydride at similar temperatures resulted only in the formation of the acetylated oxime. The structure of the product (484) was determined on the basis of two-dimensional COSY, DEPT, and 2D H-I3C chemical shift correlation experiments. The structure was also confirmed chemically via bromination which affords a mixture of the bromine adducts (485) and (486). Attempts to hydrolyze (484) under either acidic or basic conditions afforded only unchanged starting material. The formation of compound (484) from the TV-oxide (483) proceeds via a radical mechanism. This mechanism was elucidated by a study of the reaction... 

The reaction of methyl (3-hydroxypyridin-2-yl)ketone oxime (487) with thionyl chloride, trichloroacetyl isocyanate or chlorosulfonyl isocyanate gave 3-methylisoxazolo[4,5-6]pyridine (488) in varying yields dependent upon the temperature and solvent (Equation (43)) <87H(26)292l>. Trichloroacetyl isocyanate was particularly effective in the formation of compound (488) in either diethyl ether or tetrahydrofuran, at ambient temperature or at reflux, affording 60-78% yields. The treatment of 2-acetyl-3-hydroxypyridine (489) with hydroxyamine 0-sulfonic acid afforded a 1 1 mixture of compound (488) and 2-methyloxazolo[4,5-6]pyridine (490) (Equation (44)). The formation of the isomer (490) results from a Beckmann rearrangement. 

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