On the Reaction of Deacetylvindoline with Thionyl Chloride

Reaction of deacetylvindoline ( 2 ) with excess thionyl chloride gave rise to hexacyclic 6,10-dichloro-6,17-epithio-11-methoxy-1-methyltabersonine ( 4 ) as a single product in 43.5% yield. The structure was deduced from 1 H and 13 C 1D and 2D NMR experiments as well as from mass spectra. A tentative mechanism of this complex transformation was also proposed.