Rhodium-catalyzed addition of aryl boronic acids to 1,2-diketones and 1,2-ketoesters

The metal complex Rh(acac)(CO)₂ in the presence of dicyclohexylphenylphosphine provides a useful catalyst system for the addition of boronic acids to 1,2-diketones and 1,2-ketoesters. The best yields were obtained when the transformation was performed in DME/H₂O at 80 °C with 4 equiv of the boronic acid. The results discussed herein extend the scope of the addition of arylboronic acids to highly activated diketones and ketoesters. The products of the reaction are useful in the synthesis of natural products containing oxygenation next to esters or ketones.