Three new 5-1'-linked naphthyldihydroisoquinoline alkaloids (1-3) have
been isolated from the organic extract of Ancistrocladus tectorius. T
he gross structures of the compounds have been established using 1D an
d 2D NMR spectroscopy and difference NOE experiments. The absolute ste
reochemistry of 1, 2, and 3 was determined from CD spectral comparison
and chemical degradation, Evidence is presented to show that two of t
he compounds exist exclusively in the keto form at C-8 of the isoquino
line system (2b, 3b).