DIOXINS/*ISOLof West African medicinal plants. XV. Dinklacorine, a new biphenyl dibenzodioxin alkaloid from Tiliacora dinklagei

Dinklacorine was first isolated in 1974 from extracts of the roots of Tiliacora dinklagei Engl. (Menispermaceae) and designated TD-2. The ir, uv and mass spectra of dinklacorine were very similar to those of the dibenzodioxin biphenylalkaloid tiliacorine. However, the two alkaloids differed in their mp, specific rotation and nmr spectra. Methylation of dinklacorine with diazomethane afforded O-methyltiliacorine while treatment of dinklacorine with sodium methoxide and methyl iodide gave O-methyltiliacorine dimethiodide. However, prolonged treatment of tiliacorine and dinklacorine with diazoethane afforded different O-ethyl ethers. In addition, O-ethyldinklacorine dimethiodide and O-ethyltiliacorne dimethiodide were different. Furthermore, acetylation of the two alkaloids with acetic anhydride and puridine gave O-macetyl esters which were not identical. A considertation to these data and especially the mass spectral fragmentation patterns indicated dinklacorine to be a positional isomer of tiliacorine with the phenolic hydroxy group present in the biphenyl portion of the molecule on the opposite side to tiliacorine. Finally, a comparison of the cd spectra of dinklacorine and tiliacorine suggests that they have the same stereochemistry.