Synthesis and Biological Activity of 2,6-Substituted Pyridoxine Derivatives. Unusual Catalytic Role of Selenium Dioxide in the Formation of Pyridinone Methides

Among the seven-membered ketals of pyridoxine containing hydroxymethyl groups in various positions of the pyridine ring, an unusual ability of selenium dioxide to catalyze the reaction of nucleophilic substitution of the hydroxyl group by N , O -nucleophiles was found. Quantum chemical calculations have shown the possibility of the formation of selenium dioxide adducts with substrates and the formation of reactive intermediates— ortho- and para- pyridinone methides. The antioxidant and antimycotic activity of the obtained compounds was determined.