A Diels-Alder Approach to a Communesin Model: A/B-Cyclization Route

Compound 3, a model system for communesin F, was approached by using a Diels-Alder reaction for the introduction of the vicinal quaternary stereocentres. Subsequent introduction of A/B-ring system followed by D/E-ring closure gave hexacyclic system 22. All attempts to reduce this material to give compound 3 were, however, unproductive.