Sequential [6+2], [2+2], and [3+2] annulations for rapid assembly of multiple fragments.

Assembly of four components through sequential [6+2], [2+2], and [3+2] annulations on an azulenone manifold allows for five-step access to a natural product-inspired scaffold with exquisite control of the ten consecutive stereocenters. X-ray analysis was used to define the spatial arrangement of the three fragments and functional groups on this rigid scaffold.