ORGN 467

Microwave-assisted oxyanionic 5-exo cyclization/Claisen rearrangement strategy has been applied to the generation of a variety of polycyclic, cycloheptane-containing ring systems which are widespread in nature and frequently of considerable medicinal interest. This tandem process was used as the key ring-forming step to construct an advanced 6-7 bicyclic intermediate, which served as a precursor to frondosin A, a natural product isolated from the marine sponge Dysidea frondosa.