Chelation-Controlled, Palladium-Catalyzed Vinylic Substitution Reactions of Vinyl Ethers. 2-Arylethanal Equivalents from Aryl Halides

Article abstract of DOI:10.1021/jo00309a020

The regioselectivity of palladium-catalyzed arylation reactions of a series of nitrogen-containing vinyl ethers is reported.The presence of a β-amino substituent gives a profound influence on regiochemistry.Thus, the arylation of <2-(dimethylamino)ethoxy>ethene (1c) with a variety of aryl iodides and bromides provides the β-arylation products <2-<2-(dimethylamino)ethoxy>ethenyl>arenes (3) with at least 95percent selectivity and in good yields.The corresponding arylation of butoxyethene is a nonselective process giving a mixture of α- and β-substitution products.The palladium-catalyzed arylation of 1c constitutes an entry to 2-arylethanals after cleavage of the enol ether.The directing effect of the amino group is discussed in terms of chelation with the intermediate arylpalladium halide.