Ring-Size-Dependent Selectivity of the β-Hydride Elimination in Heck-Type Arylations of <i>exo</i>-Methylene Cycloketones: Chalcones versus 2-Benzyl-1-naphthols

<i>exo</i>-Methylene indanones and tetralones undergo Pd-catalyzed couplings with arene diazonium salts with divergent but in both cases high selectivity. In the case of indanones, the double bond is located <i>exo</i> to yield conformationally constrained chalcones, whereas tetralones react to afford 2-benzyl-1-naphthols via an <i>endo</i>-β-hydride elimination followed by tautomerization. Depending on the solvent used, <i>exo</i>-methylene indanones can undergo a monocoupling selectively or two successive coupling reactions with the introduction of two identical or two different aryl substituents. The second Heck coupling proceeds via an <i>endo</i>-selective β-hydride elimination to yield indenones.