1,2-Dihydro-4-quinazolinones from anthranilic amides and oxo-compounds - Studies of the ring closure using MNDO calculations

Article abstract of DOI:10.1002/ardp.19943270905

Heating of anthranilic amides 1a-c with oxo-compounds without solvent represents a simple synthetic access to 1,2-dihydro-4-quinazolinones 8-25. Under drastic conditions β-dicarbonyl compounds give the methylquinazolinones 26/27 by elimination. Thermodynamic control explicates the course of the reactions and the formation of the products. The enaminones 28/29 isolated from cyclic β-diketones are transformed to quinazolinyl pentanones 34/35 in the presence of acetic acid. The ring transformation is explained by perturbation theory.