An Efficient Palladium-Catalyzed Synthesis of Cinnamaldehydes from Acrolein Diethyl Acetal and Aryl Iodides and Bromides

The reaction of aryl iodides and bromides with acrolein diethyl acetal in the presence of Pd(OAc)(2), (n)()Bu(4)NOAc, K(2)CO(3), KCl, and DMF, at 90 degrees C until the disappearance of the acetal followed by the addition of 2 N HCl to the crude reaction mixture, affords cinnamaldehydes in good to high yields. A variety of functional groups are tolerated in the aryl halides, including ether, aldehyde, ketone, ester, dialkylamino, nitrile, and nitro groups. The presence of substituents close to the oxidative addition site does not hamper the reaction.