Synthesis ofo-Dialkenylbenzenes and Indenes Using Heck and Oxypalladation Reactions

o-Bromostyrenes 2-Br react with various alkenes in the presence of palladium catalysts to give either substituted indene 6 or o-diethenylbenzene derivatives 3, depending on the reaction conditions. Under oxidative conditions the latter can be cyclized to indene derivatives as well.