Synthesis of isocoumarin derivatives by copper-catalyzed addition of o-halobenzoic acids to active internal alkynes.

The addition of o-halobenzoic acids to active internal alkynes proceeds efficiently in the presence of CuCl(2) as a catalyst to give the corresponding isocoumarin derivatives in moderate to good yields. This strategy offers a simple, efficient route to synthesis of the isocoumarin derivatives.