BENZ[4,5]ISOQUINO[1,2-B]QUINAZOLINE-7,9-DIONE AND A REARRANGEMENT PRODUCT OF ITS HYDROLYSIS, 2-(1,8-NAPHTHALENE-DICARBOXIMIDO)BENZAMIDE

Benz[4,5]isoquino[1,2-b]quinazoline-7,9-dione, (1), C19H10N2O2, was isolated as a product of the reaction between naphthalic anhydride and anthranylamide after crystallization from dimethylformamide. Recrystallization from concentrated (95%) formic acid resulted in 2-(1,8-naphthalenedicarboximido)benzamide, (2), C19H12N2O3, as a rearrangement product of hydrolysis [alternative systematic name: 2-(1,3-dioxo-2,3-dihydro- 1H-benz[de]isoquinol-2-yl)benzamide]. The two crystallographically independent molecules of (1) [(1a) and (1b)] are substantially non-planar as a result of strong intramolecular steric repulsion between their cis-arranged carbonyl groups [the O ... O distances are 2.584(3) and 2.664(3)Angstrom, and the dihedral angles between the naphthalene and benzene nuclei are 8.75(7) and 14.46(7)degrees, respectively]. Molecule (2) is also sterically hindered with an approximately orthogonal orientation of the naphthalenedicarboximide and o-phenylene groups [dihedral angle 87.05(4)degrees] and absence of pi-conjugation between the o-phenylene and amide groups [dihedral angle 40.02 (6)degrees].