[The chemistry of antimicrobially active 1-hydroxy-2-pyridones (author's transl)]

The unsaturated delta-keto esters (3) obtained by condensation of acid chlorides with esters of di- or trialkyl-acrylic acids can be cyclized with hydroxylamine to yield 1-hydroxy-2-pyridones (4). However, in many cases a two-steps synthesis may be of advantage in preparative respect, the ketoesters being cyclized to 2-pyrones (7), which then are reacted with hydroxylamine in the presence of certain bases to give 4. The hydroxy-pyridones show pronounced antifungal activity in vitro as well as in experimental guinea pig dermatophytosis.