REACTIONS OF HETEROCYCLIC BETA-ENAMINOESTERS - A NOVEL SYNTHESIS OF PYRANOPYRIMIDINES AND RELATED-COMPOUNDS

The reaction of ethyl cyanoacetate with alpha-cyanochalcone (I) leads to the formation of a beta-enaminoester (II) via Michael addition. Compound (II) reacts with acetic anhydride to give its N-acetyl derivative (III) which cyclises to (IV) in the presence of NaH. Compound (III) reacts with ethyl bromoacetate to give (V) which gives (VI) and (VII) with NaH under different reaction conditions. The compound (VI) when refluxed with NaH gives azipinone (VIII) which can also be obtained from (VII). The compound (II) reacts with ethyl cyanoacetate, phenyl isothiocyanate and trichloroacetonitrile to yield the pyranopyrimidines (IX), (X) and (XI), respectively.