| Abstract: | The Pechmann condensation of malic acid with 1,3-dihydroxy-10-methyl-9-acridanone ( 6 ), performed during the search for a synthetic approach to 5-methoxy-2,2,11-trimethyl-2H-pyrano[2,3-b]acridan-6-one (isoacronycine, 11a ), afforded 5-hydroxy-11-methyl-2H-pyrano[2,3-b)acridan-2,6-dione ( 7 ). This is the first example of a new heterocyclic ring system in which an acridanone and a pyranone ring have been fused. Compound 7 served as the intermediate for the preparation of 11a and was readily converted into the pyranone analog 9 of isoacronycine by known procedures. Spectral and chemical evidence distinguishing 11a from acronycine ( 12a ) is presented. |
