Synthesis of indenes via palladium-catalyzed carboannulation of diethyl 2-(2-(1-alkynyl)phenyl)malonate and organic halides.

Highly substituted indenes have been prepared in good yields by the palladium-catalyzed carboannulation of diethyl 2-(2-(1-alkynyl)phenyl)malonate with aryl, benzylic, and alkenyl halides. The reaction conditions and the scope of the process were examined, and a possible mechanism is proposed.