Divergent Syntheses of Spiroindanones and 2‑Substituted 1‑Indanones by Ruthenium-Catalyzed Tandem Coupling and Cyclization of Aromatic Acids with α,β-Unsaturated Ketones

The one-step strategy for the facile syntheses of structurally diverse 1-indanones in moderate to good isolated yields was developed via a ruthenium-catalyzed tandem coupling and cyclization of simple aromatic acids with α,β-unsaturated ketones. The tandem cyclization involves one-pot sequential reactions of C–H activation, conjugate addition, Dieckmann condensation, Michael addition, intramolecular Aldol reaction, or hydrolysis. Switchable access to spiroindanones and 2-substituted 1-indanones could be achieved by manganese additive and H₂O. Mn­(II) additive is found to play an important role in this transformation, and a trace amount of water can promote the formation of 2-substituted 1-indanones. This process features the one-pot efficient construction of multiple C–C bonds, high step-economy, commercially available starting materials, and a broad substrate scope.