The 'pyrono route' to 4-hydroxy-2-quinolones and 4-hydroxy-2-pyridones

The condensation of N-substituted anilines 6, azomethines or enamines 13 wi th two equivalents of diethyl malonate yields pyrono-quinolones 8, 10-12 or pyrono-pyridones (for instance 15, 20, 23, 30, 34) in high yields and on l arge scale preparations. These pyrono-quinolones and -pyridones are therefo re excellent intermediates in the synthesis of a vast number of compounds, a number of which have potential biological activity. (C) 1999 Elsevier Sci ence S.A. All rights reserved.