Pyridinium linkage

Various eukaryotic organisms produce proteins which hydrolyse the carbon-pyridinium linkage of NAD " in a way reminiscent of the hydrolysis of... 

Each substrate was oxidized to the corresponding carbonyl compounds in good yields. Moreover, the coexisting olefin linkage remained intact upon treatment with the oxodiperoxochromium complex and no epoxy compounds were observed in the reaction mixture. Hexavalent chromium reagents such as anhydrous chromium trioxide and pyridinium... 

N-, 0-, and S-heterocyclic ligands also form [Os(NH3)5 t)2-(C,C)-L ]2+ complexes [L = 2,6-lutidine, 2,6-lutidinium, pyridinium, N-methylpyridinium, and lV-methyl-4-picolinium (85, 167), NJV -dimethylimidazolium (90), pyrrole (90, 179), IV-methylpyrrole (90, 179), thiophene (90,179), furan (90,179), and 1,3-dimethyluracil (72, 73)]. On oxidation to Os(III), arene ligands are rapidly lost from the coordination sphere, or in the case of the substituted arene ligands with good a donors, rapid linkage isomerization reactions occur (Section V,D). 

In addition to metal centres and covalent approaches, anions such as Cl may also be used as templating auxiliary linkages.80 Paul Beer and co-workers from the University of Oxford, UK, recognised that ion pairing in non-polar solvents such as acetone allowed the coordination of a neutral hydrogen bond donor such as 10.110 to the pyridinium salt 10.109, with a binding constant... 

Scheme 10.23 Strong ion-pairing in the pyridinium salt in non polar solvents allows the coordination of a neutral hydrogen bond donor and hence the creation of the precursor to a crossover in a catenane using the chloride ion as an auxiliary linkage.80...

If monoalkylanilines are treated with vinyl heterocycles, especially vinylpyri-dine, and if the heterocyclic nitrogen is then quatemized, coupling components are obtained that carry the pyridinium component on an alkylidene linkage [58], e.g., 19. 

Heterocyclic Betaines Pyridinium (Imidazolium) Azolate Inner Salts with Several Interannular Linkages ... 

Methods of synthesis leading to pyridinium (imidazolium) azolate inner salts and related compounds with a betaine character 1 can be varied. In almost all cases, their protonated compounds azolylpyridinium (imidazolium) salts with several interannular linkages 2 are useful as synthetic intermediates (Scheme 1). These quaternary salts of nitrogen heteroaromatic compounds 2 allow us to deepen the study of classical reactions and seek suitable alternatives for their preparation. 

Acharya, J., Gupta, A.K., Mazumder, A., Dubey, D.K. (2008a). In vitro reactivation of sarin inhibited electric eel acetylcholinesterase by bis-pyridinium oximes bearing methoxy ether linkages. Toxicol. In Vitro 22 525-30. 

Oligodeoxyrlbonucleotide analogues containing flexible aliphatic, non-ionic, achiral spacers are of interest as potential anti-sense agents. Analogues containing the 3 0-5 C oxyacetamide linkage were first reported in 1974, and an improved procedure for their preparation has recently been published. The pyridinium salts of 5 -azido-3 -0-carboxymethyl nucleosides... 

Recently we found that highly redueed H3PMol2O40 which was formed by the heat-treatment of pyridinium salt can catalyze the propane oxidation to acrylic acid and acetic acid selectively [24, 25]. After activation in N2 flow at 420°C for 2hr, the catalyst of HsPMo 12040 (Py) shows reduced state of molybdenum and a new stable structure in which pyridine remains as the linkage of the secondary structure. The activated H3PMoi2O40 (Py) also gives catalytic activities in the partial oxidations of ethane and isobutane to acetic acid and methacrylic acid respectively. In this paper, we will report the oxidation results of C2-C4 alkanes and discuss the roles of reduced state and aetivation of molecular oxygen over this catalyst. 

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