Microwave-Assisted [2+2+2] Cyclotrimerization Reactions
Dr. Alexander Deiters, Assistant Professor, Department of Chemistry, North Carolina State University, Raleigh, NC, USA

The transition-metal catalyzed [2+2+2] cyclotrimerization reaction provides a highly convergent approach to a variety of carbo- and heterocyclic structures. Recently, we reported Co, Rh, and Ru-catalyzed cyclotrimerizations performed on solid-supports in combination with microwave irradiation. The implementation of microwave irradiation together with the solid support affords a substantial increase in yields and extremely shortened reaction times. Moreover, catalyst activating additives, excessive heating, or light irradiation are not necessary to induce the cyclotrimerization reactions. When conducted under purely thermal conditions these reactions failed to yield significant amounts of product. This dramatic improvement through microwave irradiation cannot be just attributed to efficient heating (in fact the reaction temperature is lower than under traditional conditions), but represents one of the most pronounced examples of non-thermal microwave effects.