2-Methyl-3-hydroxypyridine-5-carboxylate

MHPCO 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase... 

Methylhydroxypyridinecarboxylate dioxygenase (E.C. 1.14.12.4 -2-Methyl-3-hydroxypyridine-5-carboxylate, NADH oxygen 2,3-oxidoreductase (decyclizing). 

Recently, many investigators have extended the early observations that the ultraviolet spectra of - and y-hydroxypyridines resemble those of their A -methyl (not the 0-methyl) derivatives. This spectral resemblance is found both in aqueous solutions and in solutions of solvents with low dielectric constants, e.g., quinol-4-one in benzene, indicating that these compounds exist predominantly in the oxo form under all conditions. These data are summarized in Table I. In contrast, 4-hydroxyquinoline-3-carboxylic acid has been tentatively concluded to exist in the hydroxy form %- pjTid-2-one-4-carboxylic acid has also been formulated as a hydroxy compound, but this has been disputed. ... 

Ochiai and Ito reported that the reaction of ethyl acetoacetate and diethyl aminomethylenemalonate (13) in the presence of hydrogen chloride gave 4-hydroxypyridine-3-carboxylate (1314) at room temperature, while in the presence of sodium in boiling benzene, the product was 2-methyl-4-hydroxypyridine-3,5-dicarboxylate (1315) (41CB1111). Aqui et al. proved... 

Amino-6-hydroxypyridine and ethyl acetoacetate were unsuccessfully reacted in a mixture of phosphoryl chloride-polyphosphoric acid. Ethyl 2-aminopyridine-3-carboxylate gave 2-methyl-4-oxo-4f/-pyrido[ 1,2-a]... 

Electron-attracting substituents should assist this reaction. However, with acetic anhydride in acetonitrile, 2-picolinic acid 1-oxide gives mainly pyridine 1-oxide and carbon dioxide, whilst the same reaction carried out under ultra-violet irradiation proceeds similarly but with the formation of a little more 2-hydroxypyridine. The methyl esters of the pyridine-carboxylic acid 1-oxides behave normally, but there is no evidence that the methoxycarbonyl group promotes the reaction, and 2-cyanopyridine 1-oxide does not react with acetic anhydride . The results of a kinetic study of the rearrangement of pyridine 1-oxide in acetic anhydride exclude the intramolecular rearrangement of the free cation (113) and also a free radical process. There remain the two possibilities of nucleophilic substitution by reaction between... 

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