Pyridinium ketoximes

Two types of amphiphilic quaternary 3-pyridinium ketoximes (253a, b) with different positioning of the hydrophobic alkyl chain have been synthesized and tested as hydrolytic micellar catalysts. A considerable positive deviation from the expected first-order curve was observed in the absorbance vs time plot when p-nitrophenyl diphenyl phosphate (252 R = Ph) and p-nitrophenyl diethyl phosphate... 

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... 

MPhenacyl-2-pyridinium salts cyclize on heating in pyridine, the methylthio group being lost (cf. Chapter 36, Section 1.3). Simultaneous Beckmann rearrangement, demethylation and cyclization converts an o-alkoxy-ketoxime into a fused oxazole ring. 

Ketoximes are converted into the corresponding ketones using two molar equivalents of pyridinium chlorochromate. " Parent aldehydes (including aliphatic) and ketones can be regenerated from aryl hydrazones using ben-zeneseleninic anhydride or hydrogen peroxide and potassium carbonate. ... 

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