Abstract
The tricyclic sesquiterpenoids (-)-ylangocamphor (1), (-)-ylango-borneol (2), and (-)-ylangoisoborneol (3) are structurally, and presumably, biogenetically very closely related to (+)-copacamphor (4), (+)-copaborneol (5), and (+)-copaisoborneol (6), respectively. Of these six compounds, only one [(+)-copaborneol (5)] has been isolated from natural sources (Pinus silvestris L.).3 We have previously reported4 the preparation of the above three “copa” sesquiterpenoids (4, 5, 6) and report here the stereoselective total synthesis of the three “ylango” sesquiterpenoids (1, 2, 3).5