A highly chemoselective C–H arylation of phenylureas has been accomplished using dual palladium–photoredox catalysis at room temperature without any additives, base or external oxidants. Regioselective C–H arylation of N,N′-diaryl substituted unsymmetrical phenylureas has also been accomplished by a careful choice of aryl groups.
Aromaticity-Dependent Regioselectivity in Pd(II)-Catalyzed C–H Direct Arylation of Aryl Ureas
作者:Pingping Jiang、Feng Li、Yongbao Xu、Qingwen Liu、Jing Wang、Hong Ding、Renfu Yu、Qifeng Wang
DOI:10.1021/acs.orglett.5b03153
日期:2015.12.4
Palladium-catalyzed C–H direct arylation generally occurs on the ortho-position of directing groups. By comparing meta-arylated products of 2-naphthyl urea to ortho-arylated products of phenyl urea, the ortho- and meta-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