STRUCTURAL AND DFT STUDY OF 1-(3-AMINO-1,4-DIOXO-1,4-DIHYDRONAPHTHALEN-2-YL)-3,4-DICHLORO-1H-PYRROLE-2,5-DIONE: HYPOTHESIS FOR THE RING CLOSURE

摘要

The reaction of 2,3-dichloromaleic anhydride with 2,3-diamino-1,4-naphthoquinone was studied and afforded to 1-(3-amino-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-3,4-dichloro-1H-pyrrole-2,5-dione (3). Experimental techniques (NMR and single-crystal structures) confirmed the structure of 3. The study was extended to explore the failure of the intramolecular cyclization of 3 to the imidazole ring. Density Functional Theory at level B3LYP/6-31G(d,p) of theory were used to examine the optimized molecular geometry and to understand the reaction mechanism which reveals that the failure of cyclization is possibly due to positive charge of the amine in addition to the high repulsion between the naphthoquinone and the maleimide oxygens.