Additive-Controlled\nDivergent Synthesis of Fluorenone-4-carboxylic\nAcids and Diphenic Anhydrides via Rhodium-Catalyzed Oxidative Dimeric\nCyclization of Aromatic Acids

A rhodium-catalyzed one-pot access to valuable polycyclic\nframeworks\nof fluorenone-4-carboxylic acids and diphenic anhydrides via the oxidative\ndimeric cyclization of aromatic acids has been developed. This transformation\nproceeded via carboxyl-assisted 2-fold C–H activation followed\nby intramolecular Friedel–Crafts or dehydration reactions.\nThe silver salt additive plays a vital role in the chemoselectivity\nof the products. Diphenic anhydride <b>3l</b> exhibits a maximum\nfluorescence quantum yield of up to 59%.