(136c) Synthesis of Aryl Esters and α,β-Alkynyl Ketones Via Palladium on Charcoal Catalyzed Carbonylation of Aryl Iodides

Aryl esters and α,β-alkynyl ketones are highly attractive synthetic targets due to their versatility in organic synthesis as well as their presence in natural products with biological activity. Among various methods to these important intermediates, Pd-phosphine complexes catalyzed carbonylation of aryl halides with alcohol, phenol or alkyne as nucleophiles is drawing considerable interest. However, Pd-phosphine complexes are often used in the reaction under homogeneous conditions. So, it is urgent to find a phosphine-free and heterogeneous catalytic system for those interesting reactions. Herein, we report Pd/C-Et₃N catalyzed alkoxycarbonylation of aryl iodides (alcohols or phenols as nucleophiles) and carbonylative Sonogashira coupling reaction of aryl iodides with terminal alkynes to afford the corresponding aryl esters and α,β-alkynyl ketones in good to excellent yields under considerably mild conditions. It was found that both electron-withdrawing and electron-donating substituents on phenol enhance the phenoxycarbonylation of iodobenzene. In addition, the recyclability of Pd/C was also demonstrated.