Crystal and molecular structure of 2-bromo-5,6-dihydro-6-methyl-4H,8H-pyrido [3,2,1-de]phenanthridin-8-one

Crystals of the title compound, C₁₇H₁₄BrNO, are monoclinic, with space groupP2₁/a,a = 14.314(5),b = 15.009(11),c = 6.596(3) Å, and = 102.39(3) °. Diffraction data were collected with CuK radiation to a Bragg angle of 77 °. The structure was solved by the heavy-atom method and refined to anR index of 0.059 for 2129 reflections. In agreement with NMR results, the C=O group is orientedanti to the benzene ring, and the methyl group at C(6) is axial. Unlike 1-(p-bromobenzoyl)-2-methyl-1,2,3,4-tetrahydroquinoline, the heterocyclic ring assumes a well defined half-chair conformation. Except for C(5) and the methyl group at C(6), the whole molecule is very nearly planar.