反应详情

This method is adapted from that of Bartulin et al., J. Heterocyclic Chem. 29:1017-1019 (1992), which is hereby incorporated by reference. A 3-benzyloxy-4-pyrone, prepared as in Method B, is added to an ethanolic solution of aqueous ammonia. The reaction mixture is stirred for approximately 3 days, concentrated under reduced pressure, triturated with acetone, and the solid recrystallized from ethanol to yield the corresponding 3-benzyloxypyrid-4-one. To a solution of this pyrid-4-one in aqueous ethanol containing one equivalent of sodium hydroxide was added an equivalent of n-alkyl bromide. The reaction mixture was heated under reflux for 24 hours after which it was cooled, concentrated under reduced pressure, and extracted with an appropriate solvent. After washing, the organic phase with water, it is dried over magnesium sulfate. The product is obtained upon concentration of the solution under reduced pressure. Crude 1-alkyl-3-benzyloxypyrid-4-one in acetic acid containing 40% hydrobromic acid is then heated on a steam bath for 30 minutes. The 1-alkyl-3-hydroxypyrid-4-one precipitates and is subsequently recrystallized from benzene in good yield with a narrow melting point and appropriate NMR spectrum. This is shown in the following synthesis: ##STR6##

1. concentrationconcentrated under reduced pressure
2. customtriturated with acetone
3. customthe solid recrystallized from ethanol