Reaction of dichloromaleic anhydride with 1,8-diaminonaphthalene: Synthesis and X-ray diffraction structure of 8,9-dichloropyrrolo[1,2-a]perimidin-10-one

The reaction of dichloromaleic anhydride with 1,8-diaminonaphthalene in refluxing toluene or 1,2-dichloroethane produces the new heterocyclic compound 8,9-dichloropyrrolo1,2-a]perimidin-10-one in low yields. 8,9-Dichloropyrrolo1,2-a]perimidin-10-one has been isolated by column chromatography and characterized in solution by IR, ¹H NMR, and UV/vis spectroscopies. The solid-state structure was unequivocally established by single-crystal X-ray diffraction analysis. 8,9-Dichloropyrrolo1,2-a]perimidin-10-one crystallizes in the monoclinic space group P2 ₁/c, a = 7.475(1)Å, b = 10.650(2)Å, c = 14.468(2)Å, = 94.478(2)°, V = 1148.3(3) ų, Z = 4, and d _calc = 1.672 Mg/m³; R = 0.0289, R _w = 0.0762 for 1644 reflections with I > 2(I). The nature of the HOMO and LUMO in 8,9-dichloropyrrolo1,2-a]perimidin-10-one has been determined by extended Hückel molecular orbital calculations, and these data are discussed relative to the cyclic voltammetric data obtained at a platinum electrode.