Optimal conditions were developed for the synthesis of 11 H-isoindolo [2, 1-a] benzimidazol- 11-one, 5 H-isoindolo [2, 1-a][3, 1] benzoxazine-5, 11 (6a H)-dione, and 6, 6a- dihydroisoindolo [2, 1-a] quinazoline-5, 11-dione derivatives in the reaction of substituted 2- formylbenzoic acids with o-phenylenediamine, anthranilic acid, and anthranilamide, respectively. The bifolded structure of 6, 6a-dihydroisoindolo-[1, 2-a] quinazoline-5, 11- ...