Transition Metal Catalyzed Dimerization of Allenyl Ketones

摘要

Furans are present in many natural products and important Pharmaceuticals as well as in flavorings and fragrances. Furthermore, they are very popular synthetic building blocks. Therefore a great deal of effort has been devoted to the development of new synthetic methods for the formation of furans. A milestone in the area of transition metal catalyzed syntheses of furans was the discovery by Marshall that the readily available allenyl ketones 1 can be isomerized selectively to furans by using Rh~I orAg~I catalysts. Several years prior to this discovery, similar rearrangements had been observed by Jullien et al. and Huntsman et al. when allenyl ketones were subjected to flash vacuum thermolysis.