X-ray diffraction and total 1H and 13C NMR assignment of (RS)-5,6-dihydro-7,8-dimethoxy-5-methyl-6-(2-oxopropyl)-(2,3-methylenedioxyphenyl)-[c]-phenanthridine ((RS)-6-acetonyldihydrochelerythrine)

The X-ray diffraction structure of (RS)-5,6-dihydro-7,8-dimethoxy-5-methyl-6-(2-oxopropyl)-(2,3-methylenedioxyphenyl)-[c]-phenanthridine ((RS)-6-acetonyldihydrochelerythrine), isolated as an artifact from Bocconia Arborea, is reported. This compound crystallizes as orthorhombic system, space group Pna2(1), with a = 13.216(2) Angstrom, b = 7.6547(10) Angstrom, c = 20.096(3) Angstrom. The phenanthridine central ring presents a distorted boat conformation, which gives rise to two planes with 21.30degrees between them. The acetonyl group at the six position forms weak C-H...O and C-H...pi-ring interactions. The title compound was completely characterized in solution by H-1 and C-13 and 2D NMR experiments.