Unprecedented microwave effects on the cycloaddition of fulvenes. A new approach to the construction of polycyclic ring systems.

[reaction: see text] Novel cycloaddition reactions between fulvenes and various alkenes and alkynes are promoted by the use of microwave irradiation. These processes result in the formation of intriguing polycyclic ring systems such as those found in isobarbatene, alcyopterosin, and enokipodin A. Importantly, these reactions do not occur under conventional thermolytic conditions.