Ring-Size-Dependent Selectivity of the β-Hydride Elimination in Heck-Type Arylations of -Methylene Cycloketones: Chalcones versus 2-Benzyl-1-naphthols.

-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 to yield conformationally constrained chalcones, whereas tetralones react to afford 2-benzyl-1-naphthols via an -β-hydride elimination followed by tautomerization. Depending on the solvent used, -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 -selective β-hydride elimination to yield indenones.