Cycloaddition in condensed isoindoles 1. Preparation of 2-aryl-3-methyl-4-oxo-3,4-dihydroquinazoline
Reaction of 6-methyl-5,6-dihydroisoindolo[2,1-a]quinazolin-5-one with maleimide derivatives has been studied under conditions of thermodynamic control. X-ray diffraction structural analysis showed that the reaction products are 2{2-[(E)-1-R-2,5-dioxopyrrolidinidenemethyl]phenyl}-3-methyl-4-oxo-3,4-dihydroquinazolines. These products are supposed to be formed by rearrangement of the corresponding Diels-Alder adducts formed involving the isoindole part of the molecule.