In this study, 1-amino-5-benzoyl-4-phenylpyrimidin-2(1H)-one (1) was synthesized from 4-benzoyl-5-phenylfuran-2,3-dione and 1-(1-phenylethylidene)semicarbazide in benzene. Since pyrimidine-based Schiff bases have an extensive working range, two new compounds (2, 3) were synthesized from the reaction of this starting material (1) with 3-bromobenzaldehyde or 4-chlorobenzaldehyde. The structures of the synthesized new compounds were clarified employing FT-IR, H-1 NMR, C-13 NMR, and elemental analysis. HOMO, LUMO, and energy gap between them was calculated as theoretical. On the other hand, conformation analysis studies of compounds were carried out for determining the energies of the conformers.