Model Studies for the Synthesis of Tetracyclic Sesquiterpenes

Abstract

While considering potential routes for the synthesis of several tetracyclic sesquiterpenes (1–3),² we were attracted by the possibility that this basic ring system might be constructed by solvolysis of an appropriately substituted norbornene derivative. By this scheme the homoallylic carbonium ion of a norbornenyl-nortricyclyl system would be captured by an attached carbon nucleophile to form the final two rings of these highly

condensed molecules in a single step. Although nucleophilic capture could presumably occur at either end of the fluxional homoallylic ion, the generally high proportion of nortricyclic material formed by solvent capture in simpler systems led us to anticipate a similar result int he present case.³