METHOD OF PREPARING 1-HYDROXY-PYRID-2-ONES Russian patent published in 2000 - IPC

FIELD: organic chemistry. SUBSTANCE: described is method of preparing compounds of formula I: which are well known for their bacterial and antifungal activities wherein R¹ is branched or unbranched alkyl having 1 to 17 carbon atoms, branched or unbranched alkyl having 2 to 17 carbon toms, cycloalkyl having 3-8 carbon atoms in the ring, said cycloalkyl residue being not substituted or substituted by means of 1-3 alkyl residues each, depending on circumstances, with 1-3 carbon atoms, phenyl, phenyloxy (C₁-C₄) alkyl or phenyl-(C₁-C₄) alkyl, phenyl, phenyloxy-(C₁-C₄) alkyl and phenyl-(C₁-C₄) alkyl residues being not substituted or substituted in the aromatic ring with by means of 1-3 (C₁-C₆) alkyl, benzyl, (C₁-C₆) alkoxy, phenoxy or halide residues, said cycloalkyl, phenyl, phenyloxy (C₁-C₄) alkyl residues being connected directly or through methylene or ethylene group with pirydone ring; and R² is hydrogen atom, alkyl having 1-6 carbon atoms, alkenyl having 2-6 carbon atoms or benzyl residue by reacting pyrone of formula II: , residues R¹ and R² are as defined in formula I for corresponding residues R¹ and R², with hydroxyammonium salt in solvent and in the presence of alkali metal carbonate and/or alkali metal hydrocarbonate in amount of 0.8-5 equivalents calculated for hydroxyammonium salt, and reaction is carried out in the presence or organic acid or salt thereof. Method makes it possible to make process more profitable. EFFECT: more efficient preparation method. 10 cl, 30 ex, 3 tbl