Ruthenium(II)-Catalyzed Cyclization of Aromatic Acids with Allylic Acetates via Redox-Free Two-Fold Aromatic/Allylic C-H Activations: Combined Experimental and DFT Studies.

A Ru(II)-catalyzed, redox-free, two-fold aromatic/allylic C-H bond activation of aromatic acids with allylic acetates to give ( Z)-3-ylidenephthalides is described. In the reaction, H was formed as a side product. The detailed mechanistic investigation and DFT studies including the transition-state analysis support the postulate that the C-H allylation takes place at the ortho position of aromatic acids with allylic acetates followed by intramolecular cyclization at the allylic C(sp)-H via a π-allylruthenium intermediate.