Abstract

Boldine (5,6,6a,7-tetrahydro-1,10-dimethoxy-6-methyl-4H-dibenzo[de,g]quinoline-2,9-diol) is an aporphine alkaloid noted for its antioxidant properties. A salient feature of the molecule is the non-planarity of the biphenyl system, which exhibits a dihedral angle of 151.1(8)° between the least-squares planes of the two benzenoid rings and torsion angles of 25.7(3), -150.6(2), -155.9(2) and 27.8(3)° about the biphenyl bond. Methoxy C atom C13 lies only 0.195(4) Å above the mean plane of the ring to which it is attached, with torsion angles about the C10-O2 bond of 168.6(2) and -11.3(4)°. Methoxy C atom C14 is displaced -1.101(3) Å from the corresponding ring plane, with torsion angles about the C1-O3 bond of 102.3(2) and -79.7(3)°. All intramolecular bonds and angles are within the expected range.