Cu(OAc)2-Mediated benzimidazole-directed C–H cyanation using 2-(4-methylpiperazin-1-yl)acetonitrile as the cyano source

Abstract

A new protocol for the Cu(OAc)₂-mediated cyanation of arenes using benzimidazole as the directing group with 2-(4-methylpiperazin-1-yl)acetonitrile as the cyano source was developed. A series of cyano derivatives were facilely and conveniently obtained in moderate to good yields by using this method. The C–H activation catalytic system was originally applied to the C(sp²)–H cyanation of the aryl/heteroaryl to synthesize 2-(1H-benzo[d]imidazol-2-yl)aryl nitriles. There were 19 new compounds in the synthesized 20 cyanide products. In this reaction, 2-(4-methylpiperazin-1-yl)acetonitrile as the cyano source was originally employed in the C(sp²)–H cyanation of the arenes. In addition, a fluorescent material 5a was obtained by derivative reactions of the obtained cyanide product 3.