An efficient approach to dihydrofurocoumarins via palladium-catalyzed annulation of 1,3-dienes by o-iodoacetoxycoumarins.

The palladium-catalyzed annulation of 1,3-dienes by o-iodoacetoxycoumarins provides an efficient method for the synthesis of biologically interesting dihydrofurocoumarins. The presence of the acetyl group on the phenolic oxygen and the use of silver carbonate as a base are crucial for this process. This reaction is very general and regio- and stereoselective, and a wide variety of terminal, cyclic, and internal 1,3-dienes can be utilized. Derivatization of the annulation products provides an efficient approach to numerous analogues of natural products.