Aromaticity-Dependent Regioselectivity in Pd(II)-Catalyzed C–H Direct Arylation of Aryl Ureas

Palladium-catalyzed C–H direct arylation generally occurs on the <i>ortho-</i>position of directing groups. By comparing <i>meta</i>-arylated products of 2-naphthyl urea to <i>ortho-</i>arylated products of phenyl urea, the <i>ortho-</i> and <i>meta-</i>regioselectivity of aryl ureas were found to depend on the aromaticity of the corresponding aryl substituents. Thus, aromaticity is a new factor which can affect the regioselectivity in C–H direct arylation. The finding was further confirmed by regioselective direct arylation of indole and pyrrole derivatives