Ketoximes, diaryl

Die Hydrolyse wird bei aliphatischen Oximen im alkalischen, bei Aryl-aldoximen und -ketoximen wegcn der alkalisch auftretenden Disproportionierung zum Amin und Oxim (s. a. S. 372) im sauren durchgefiihrt. Einigc, z. B. Diaryl-ketoxime, werden nur bei hoherer Temperatur reduziert. 

Satisfactory with 1 -phenylethanone (acetophenone) oxime and other diaryl ketoximes acid catalysts include HCI, H2S04, PCI5, H3PO< (Section 24-3C). 

The reduction of ketoximes to primary amines by zinc dust often proceeds better with coned, ammonia solution than with acid. " The reaction proceeds particularly well with diaryl ketoximes (80-90% yield) with aryl alkyl ketoximes yields are lower (50-60%). The oxime, zinc, ammonium acetate, and coned, ammonia solution are refluxed in ethanol. 

Diaryl ketoximes 944 The ketone (0.01 mole) and hydroxylamine hydrochloride (0.011 mole) are warmed in a mixture of pyridine and anhydrous ethanol until a clear solution is obtained 4-5 ml of each solvent usually suffice. The mixture is warmed for 2 h on the steam-bath, then the solvent is removed, and the residue (usually forming good crystals) is washed with water. 

Reactions with alkyl aryl ketoximes are less selective than reactions with diaryl ketoximes. 

Diaryl ketoximes are successfully vinylated with acetylene under pressure in the system KOH/DMSO (60°C-80°C, 5-7 min) to selectively afford the corresponding 0-vinyldiaryl ketoximes in up to 90% yields (Scheme 1.136) [314]. 

SCHEME 1.136 Vinylation of diaryl ketoximes with acetylene in the KOH/DMSO system. 

When diaryl tellurium dichlorides and equimolar amounts of ketoximes were stirred for 3 h at 20° in benzene in the presence of triethylamine as hydrogen-chloride scavenger, diaryl tellurium ketoximate chlorides were obtained as white solids2. 

Diaryl tellurium dichlorides and the sodium salts of ketoximes reacted in benzene at 20° to give diaryl tellurium dioximates2. These oximates are white, crystalline solids. 

Good to excellent yields of jfc/M-difluoridcs are obtained from the reaction of ketoximes with NO BF4, (HF) /pyridine. The reactions are carried out under very mild conditions (rt, Nj atmosphere. 5 h) and the method is applicable to alkyl aryl (entry 7). diaryl (entry 8), and dialkyl ketoximes (entries 1 -6). In the ca.se of aldoximes. oxidation occurs and carboxylic acids are obtained. The concentration of the hydrogen fluoride in pyridine has an important effect on the yield of the reaction. The best results are obtained in the case of pyridinium poly(hydrogcn fluoride) with 60 wt % hydrogen fluoride. With lower concentrations, the major... 

The addition of ZnBr2 to the tandem 1,3-azaprotio cyclotransfer-cycloaddition of a ketoxime with divinyl ketone results in rate enhancement and the exclusive formation of l-aza-7-oxabicyclo[3.2.1]octan-3-ones7 The 1,3-dipolar cycloaddition of 1-aza-l-cyclooctene 1-oxide with alkenes produces the corresponding isoxazolidines in high yields with a minimum of polymeric material. The cycloaddition of thiophene-2-carhaldehyde oxime with acetonitrile and methyl acrylate produces the 1,3-dipolar adduct, suhstituted isoxazolidines, and not the previously reported 4 - - 2-adducts. Density functional theory and semi-empirical methods have been used to investigate the 3 + 2-cycloaddition of azoxides with alkenes to produce 1,2,3-oxadiazolidines. The 3 -h 2-cycloaddition of a-nitrosostyrenes (62) with 1,3-diazabuta-1,3-dienes (63) and imines produces functionalized cyclic nitrones (64) regioselectively (Scheme 22). The first imequivocal 1,3-dipolar cycloaddition of sulfines involves the reaction of 2,2,4,4-tetramethyl-3-thioxocyclobutanone S-oxide with diaryl thioketones to produce... 

The Beckmann rearrangement of ketoximes to the corresponding amides (31), the Fischer indole cyclization, isomerization of epoxides to the corresponding aldehydes, ketones, or alcohols, hydration and ammo-nolysis of epoxides, oxygen-sulfur interchange, formation of diaryl-ureas and -thioureas from condensation of aniline and carbonyl sulfide, and olefin carbonylation occur over zeolite catalysts (62). The oxo reaction over rhodium and cobalt containing zeolites recently has been claimed (22). 

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