Rhodium-Catalyzed Annelation of Benzoic Acids with α,β-Unsaturated Ketones with Cleavage of C-H, CO-OH, and C-C Bonds.

In the presence of a [Cp*RhCl2 ]2 catalyst, the Lewis acid In(OTf)3 , and the mild base Na2 CO3 , aromatic carboxylates and α,β-unsaturated ketones undergo a unique hydroarylation/Claisen/retro-Claisen process to give the corresponding indanones. In this carboxylate-directed ortho-C-H annelation, the C-COR bond of the ketone and the CO-OH group of the aromatic carboxylate are cleaved, and the hydroxy group is transferred from the aromatic to the aliphatic acyl residue. This reactivity is synthetically useful, particularly when starting from cyclic ketones, which are converted into indanones bearing aliphatic carboxylate side chains, thus greatly increasing the molecular complexity of aromatic carboxylates in a single step.