Reaction of Anthranilamides with Levulinic Acids. Synthesis of 2,3,3a,4-Tetrahydropyrrolo[2,1-b]quinazoline-1,9-diones

The reaction of 2-(methylamino)benzamide with levuiinic acid gave 3a,4-dimethyl-2,3,3a,4-tetrahydropyrrolo[2,1-b]quinazoline-1,9-dione (2). 3a-Methyl-2,3,3a,4-tetrahydro-pyrrolo[2,1-b]quinazoline-1,9-dione (6) was prepared by the method shown in Chart 3. The compounds 2 and 6 were different from authentic samples A and B prepared by the method reported by previous workers. The real structures of A and B were found to be 3a-methyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-1,5-dione (9) and 3-(2,3-dimethyl-4-oxo-1,2,3,4-tetrahydro-2-quinazolinyl)propionic acid (10), respectively.