Arboflorine, an Unusual Pentacyclic Monoterpenoid Indole Alkaloid Incorporating a Third Nitrogen Atom

[structure: see text] A new indole alkaloid, arboflorine, possessing a novel pentacyclic carbon skeleton and incorporating a third nitrogen atom was obtained from the Malayan Kopsia arborea. The structure was established by spectroscopic analysis, and a possible biogenetic pathway from a preakuammicine-type precursor is presented.