Direct synthesis of protected arylacetaldehydes by tetrakis(phosphane)palladium-catalyzed arylation of ethyleneglycol vinyl ether

A range of aryl bromides undergo Heck reaction with ethylene glycol vinyl ether, in the presence of [PdCl(C3H5)](2)/ cis,cis,cis-1,2,3,4-tetrakis [(diphenylphosphanyl)methyl]cyclopentane as catalyst, to give regioselectively protected arylacetaldehydes in good yields. The beta-arylation products were obtained in with 93-100% selectivity with electron-poor aryl bromides or heteroaryl bromides. Furthermore, this catalyst can be used at low loading, even for reactions with sterically hindered aryl bromides. The aryl vinyl ether intermediates undergo subsequent ketalisation to give the corresponding 2-benzyl,-1,3-dioxolane derivatives. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).