11-Methyl-2,3-benzodipyrrin-1-one

Abstract

The title compound {alternative names: 11-methyl-2,3-benzopyrromethenone and 3-[(1-methylpyrrol-2-yl)methylidene]-2,3-dihydro-1H-isoindol-1-one}, C(14)H(12)N(2)O, was prepared by the base-catalysed condensation of phthalimidine with 2-formyl-1-methylpyrrole; yellow orthorhombic crystals, space group Pbca, were obtained from ethanol. The molecule is almost planar, having Z(-)antiperiplanar geometry. The molecules are arranged in pairs with intermolecular hydrogen bonding between lactam functions. Comparison with literature values for polyalkyldipyrrin-1-ones shows that, apart from the local constraints of the benzene ring, the fused benzo ring has little effect on the molecular dimensions of the dipyrrin-1-one skeleton.