First synthesis of an ABCE ring substructure of daphnicyclidin A.

The ABCE tetracyclic ring system of daphnicyclidin A was prepared using an intramolecular (4 + 3) cycloaddition of an oxidopyridinium ion as the key step. This route consists of a 10-step synthesis with an overall yield of 20.2%. This result offers support for the use of this strategy for total synthesis of daphnicyclidin A.