Regioselective C-C Bond Construction Of N-Aryl Amides

Direct functionalization of C-H bonds to synthesize C-C bonds plays a very important role in organic synthesis. In this reaction, simple raw material can be used to synthesize complex organic compounds, also the efficiency of transformation can be improved. In this paper, we mainly study on the regioselective C-C bond construction of N-aryl amide. In the first part, we studied the effect of aromaticity on the direct arylation of aromatic amide. In the second part, we have developed a new method for the synthesis of imine derivatives by transition metal catalyzed C-H olefination/ dearomatization of aromatic amides with diarylacetylenes.Firstly, using aryl boric acids as arylation reagents, we studied the reaction of C-H direct arylation of N-aryl amide at room temperature, getting a series of arylation products with isolated yields up to 80%. By comparing meta-arylated products of 2-naphthyl urea to ortho-arylated products of phenyl urea, we came to the conclusion that aromaticity is a new factor which can affect the regioselectivity in C-H direct arylation.Secondly, we achieved an unprecedented approach for the synthesis of imine derivatives via a Pd(II)-catalyzed dearomatization reaction of N-aryl ureas with internal alkynes. We examined the scope of substrates, getting a series of products with isolated yields up to 95%, and we have carried out a detailed study of the reaction mechanism.From the above studies,we have studied two different parts of works. we infer that the regioselectivity of aryl ureas were found to depend on the aromaticity of the corresponding aryl substituents. we have reported the first example for the synthesis of imine derivatives using aryl urea as substrates.