Winchinines A and B, two unusual monoterpene indole alkaloids with a third nitrogen atom from Winchia calophylla

Abstract

Two novel monoterpenoid indole alkaloids (MIAs) with a third nitrogen atom, winchinines A (1) and B (2), along with three known ones (3–5) were isolated from the twigs and leaves of Winchia calophylla. Compound 1 is the first natural MIA possessing a 6/5/6/5/6/5 hexacyclic ring system with an oxazolidinone unit. Compound 2 is an unprecedented cyano-substituted aspidosperma-type alkaloid. Their structures with absolute configurations were elucidated by means of NMR spectroscopy, single crystal X-ray diffraction, and electronic circular dichroism data analyses.