SYNTHESIS OF PYRANO(4,3-B)PYRAN-4,5-DIONES

3-Acyl-4-hydroxy-6-methyl(or phenyl)-2H-pyran-2-ones (III) have been converted into 2,3,7-trisubstituted-4H,5H-pyrano-(4,3-b)pyran-4,5-dione perchlorates (IV) using acetic anhydride and perchloric acid mixture. The perchlorates (IV) on boiling with aqueous ethanolic solution gave the corresponding pyranopran-4,5-diones (II) in moderate to excellent yields.

M SIDDIQ ,A W KHAN ,P F G PRAILL ,