Copper-Catalyzed Preparation of gamma-Alkylidenebutenolides and Isocoumarins under Mild Palladium-Free Conditions
Abstract
A general and efficient copper(I)-catalyzed cross-coupling and heterocyclization reaction of terminal alkynes and b-iodo-a,b-unsaturated acid dérivatives has been developed under very mild conditions. This method provides easy access from good to excellent yields of a variety of 5-ylidenebutenolides and 3-substituted isocoumarins with excellent regioand stereoselectivity. This procedure does not require the use of any expensive supplementary additives, and is palladium-free.