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Synthetic approaches to three cyclic 2,4,5,6-tetrakis(hydroxymethyl)pyridin-3-ol acetonides were developed. Among seven possible mono- and diketals, six-membered cyclic ketal incorporating the hydroxymethyl group in the 4-position turned out to be the most thermodynamically favorable. The experimental data were consistent with the results of quantum-chemical calculations of the Gibbs energies of formation of different acetonides. The structure of the isolated compounds was studied by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Methods for the preparation of three cyclic 2,3,4-tris(hydroxymethyl)-6-methylpyridin-5-ol acetonides have been developed by variation of the reaction conditions. The six-membered acetonide turned out to be thermodynamically more stable than the seven-membered acetonide and bis-acetonide. The experimental data were consistent with the results of quantum-chemical calculations. The structure of the isolated compounds was proved by X-ray analysis. [ABSTRACT FROM AUTHOR]

The three-component condensation of diethyl 2,4,6-trioxoheptanedicarboxylate with salicylaldehyde and its 3,5-dichloro-, 3-methoxy-, and 5-methoxy-substituted derivatives in EtOH in the presence of ammonium acetate affords tricyclic products, viz., tetrahydrobenzo[ e]-pyrano[4,3- b]pyridines. In the reaction with 3-nitrosalicylaldehyde, the intramolecular closure of the pyran ring does not occur due to the deactivation of the hydroxy group by the nitro group, and this reaction stops at the formation of the monocyclic product, viz., tetrahydropyridin-4-one. [ABSTRACT FROM AUTHOR]

Condensation of diethyl 2,4,6-trioxoheptanedioate with 4-methoxy-2-(4-methylphenyliminomethyl)-phenol in acetone gave diethyl 5-hydroxy-9-methoxy-1-(4-methylphenyl)-4-oxo-1,4a,5,10b-tetrahydro-4 Hchromeno[ 4,3- b]pyridine-2,5-dicarboxylate as a mixture of diastereoisomers. The major (4a R,5 R,10a R)-isomer was isolated as individual substance, and its structure was proved by X-ray analysis. [ABSTRACT FROM AUTHOR]

It was found that benzoic acid hydrazides rapidly and quantitatively react with electrogenerated chlorine and bromine under the conditions of galvanostatic coulometry. Benzoic acid hydrazides were determined in model solutions. A good precision (RSD varied from 1 to 6%) allowed coulometry to be applied to the determination of isonicotinic acid hydrazide in isoniazid tablets and isonicotinic acid 3-methoxy-4-hydroxybenzylidenehydrazide in phthivazid tablets. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the development of the new synthesis method of pyridoxine IV hydroxymethylated. It states that the study has determined three stages which include the acetonide protection of hydroxymethyl groups, the hydroxymethylation of the seven-membered cyclic pyridoxine, and the removal of the protection in the acid medium. The article also features the research on the x-ray diffraction (XRD) analysis of crystal of compounds.