Alistonitrine A, a caged monoterpene indole alkaloid from Alstonia scholaris.

Alistonitrine A, a new monoterpene indole alkaloid incorporating a third nitrogen atom, was isolated from the leaves of Alstonia scholaris and found to possess an unprecedented caged skeleton with a unique 6/5/6/5/5/6 ring system. Its structure and absolute configuration were established by extensive spectroscopic analyses and electron circular dichroism calculations. A plausible biogenetic pathway has been proposed for the biosynthesis of alistonitrine A from picrinine.