2-Alkyl-3-hydroxy-4-pyridinones

Alkyl-3-hydroxy-4-pyridinones can be converted into analogues containing, e.g., anilino-, phenylthio-, or 2-hydroxyethylthio-substitu-ents by silver(I) oxidation (Ag20 in ethanol) followed by Michael addition (71). In aminomethylation of 3-hydroxy-4- and -2-pyridinones under Mannich conditions the position of substitution can be tailored, by reaction conditions to position C4 or C6, or by converting the OH into OMe, which directs substitution to C5 (72). 

Despite their importance in many pharmacological uses and potential applications, solubilities of hydroxypyranones, hydroxypyridinones, and their complexes have not been extensively and systematically investigated and established. This situation contrasts sharply with that for partition coefficients, as will become apparent in the following section. The solubility of maltol in water is approximately 0.1moldm , of ethyl maltol 0.13 mol dm, at 298 K. 1,2-Alkyl-3-hydroxy-4-pyridinones show the expected decrease in water-solubility as the sizes of the alkyl groups increase solubilities - in water at 298 K - of l-aryl-2-methyl-3-hydroxy-4-pyridinones decrease from 9 X 10 mol dm for the 1-phenyl compound through 6 x lO- moldm for l-(4 -tolyl) to 6 x 10 mol dm for l-(4 -re-hexyl-phenyl) (37). 

Pyridin-4-one, 1 -hydroxy-2,6-dimethyl-hydrogen-deuterium exchange reactions, 2, 196 Pyridin-4-one, 1-methyl-hydrogen-deuterium exchange, 2, 287 pK 2, 150 Pyridin-2-one imine tautomerism, 2, 158 Pyridin-2-one imine, 1-methyl-quaternization, 4, 503 Pyridin-4-one imine tautomerism, 2, 158 Pyridinone methides, 2, 331 tautomerism, 2, 158 Pyridinones acylation, 2, 352 alkylation, 2, 349 aromaticity, 2, 148 association... 

Partition coefficients have been measured for tris-maltolatoiron(III) and tris-ligand complexes derived from a range of A-substituted 3-hydroxy-4-pyridinones, particularly (251) with R and R variously Me, Et, pj 1325,1326 j- nge of complexes with alkyl (up to A-butyl) or... 

Johnson, A.R., O Sullivan, B., and Raymond, K.N. (2000) Synthesis of a ligand based upon a new entry into the 3-hydroxy-N-alkyl-2(lH)-pyridinone ring system and thermodynamic evaluation of its gadolinium complex. Inorganic Chemistry, 39, 2652-2660. 

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