Isoquinoline alkaloids from Ancistrocladus tectorius

Abstract Two new alkaloids were extracted from the bark of Ancistrocladus tectorius , 6,8-dimethoxy-3-hydroxymethyl-1-methylisoquinoline and the naphthylisoquinoline, 4′- O -demethylancistrocladine, together with the known isoquinolines, 6,8-dimethoxy-1,3-dimethylisoquinoline and ( S )-6,8-dimethoxy-1,3-dimethyl-3,4-dihydroisoquinoline, which, however, have never been isolated from a natural source. The structures of the new alkaloids, as well as the absolute stereochemistry of 4′- O -demethylancistrocladine were established by spectroscopic means and chemical correlations.