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.本研究开发了一种通用的钯催化合成多取代α,β-不饱和羰基化合物的方法。与已知的不饱和羰基化合物与芳基卤化物的Heck型偶联反应不同，本方法可采用稳定且易获取的饱和羰基化合物作为烯烃源。此外，该反应仅需低催化剂用量即可顺利进行，且无需使用任何昂贵的金属氧化剂或配体。在本研究所开发的反应条件下，多种饱和醛、酮及酯均可与芳基卤化物发生该反应，以中等至优异的收率得到α,β-不饱和羰基化合物。推测的反应机理包含钯催化脱氢步骤，随后进行Heck型交叉偶联反应。