Palladium-Catalyzed Dehydrogenative β‑Arylation of Simple Saturated Carbonyls by Aryl Halides

A versatile
palladium-catalyzed synthesis of highly substituted α,β-unsaturated
carbonyl compounds has been developed. In contrast to the known Heck-type
coupling reaction of unsaturated carbonyl compounds with aryl halides,
the present methodology allows the use of stable and readily available
saturated carbonyl compounds as the alkene source. In addition, the
reaction proceeds well with low catalyst loadings and does not require
any expensive metal oxidants or ligands. A variety of saturated aldehydes,
ketones, and esters are compatible for the reaction with aryl halides
under the developed reaction conditions to afford α,β-unsaturated
carbonyl compounds in good to excellent yields. A possible reaction
mechanism involves a palladium-catalyzed dehydrogenation followed
by Heck-type cross couplings.