In this study,pyrrolo[1,2-a] perimidin-10-one compounds were synthesized by the reaction of maleic anhydride with heterocyclic ketene aminals (HKAs) containing perimidine moiety. The structures of these novel compounds were confirmed by IR, H-1 NMR, C-13 NMR, UV and elemental analysis. In order to develop a more understanding of the energetic and structural properties of pyrrolo[1,2-a]perimidin-10-ones, a series of theoretical calculations were performed. Their geometries have been optimized by using Hartree-Fock and Density Functional Theory. The structures of possible conformations have been examined to predict lower-lying energy structure of the title molecule. Structural parameters and energetics, such as HOMO and LUMO energies, were analyzed comparing the structural isomers.