One-step synthesis, characterization and X-ray analysis of benzo[de]benzo[4,5]imidazo[2,1-a]isoquinolin-7-ones

Abstract

Two isomeric compounds of methoxy substituted benzo[de]benzo[4,5]imidazo[2,1-a] -isoquinolin-7-one were obtained from the one-step ring closure reaction of 2-(2-acetamino-5-methoxyphenyl)benzo[de]isoquinoline-1,3-dione under acidic condition. Their structures were characterized by using HRMS, NMR spectra analyses together with single crystal X-ray diffraction. Compound 2 crystallizes in the monoclinic P2 (1)/n space group with the crystal cell parameters a=8.3311(11)Å, b=7.6646(10)Å, c=21.201(2)Å, α=90.00°, β=95.7380(10)°, γ=90.00°, V=1347.0(3)Å3 and Z=4. Compound 3 crystallizes in the monoclinic space group P2 (1)/c with the crystal cell parameters a=3.8270(3)Å, b=15.8361(14)Å, c=28.559(3)Å, α=90.00°, β=94.1090(10)°, γ=90.00°, V=1726.4(3)Å3 and Z=4. X-ray results indicated that it exist non-classically intermolecular interactions in the molecules of the two compounds. The substitution position of methoxy group has no obvious influence on the whole molecular planarity, but results in great different formation modes of their intermolecular interactions and structural stabilization.