Assembly of 3-Substituted Isocoumarins via a CuI-Catalyzed Domino Coupling/Addition/Deacylation Process

An efficient strategy for the synthesis of a variety of 3-substituted isocoumarins has been developed. The reaction proceeded from <i>o</i>-halobenzoic acids and 1,3-diketones via a copper­(I)-catalyzed domino reaction in DMF under the action of K₃PO₄ at 90–120 °C without a ligand to afford the corresponding 3-substituted isocoumarin derivatives in good to excellent yields. <i>o</i>-Halobenzoic acids could be <i>o</i>-iodobenzoic acid, <i>o</i>-bromobenzoic acid, and <i>o</i>-chlorobenzoic acid derivatives. 1,3-Diketones could be alkyl- and aryl-substituted 1,3-diketones