Palladium/di-1-adamantyl-n-butylphosphine-catalyzed reductive carbonylation of aryl and vinyl halides

A general and efficient palladium-catalyzed reductive carbonylation with low catalyst loadings (0.5 mol % Pd or below) has been developed. The formylation of aryl and heteroaryl bromides proceeds smoothly in the presence of palladium/di-1-adamantyl-n-butylphosphine at ambient pressure of synthesis gas to afford the corresponding aromatic aldehydes in good yields and excellent selectivity. In addition, vinyl halides react under similar conditions to form α,β-unsaturated aldehydes in good yield.