A fast and efficient CuI-catalyzed intramolecular C—N coupling reaction of N-(2-bromoaryl)-1H-pyrazol-5-amines to synthesize benzo[4,5]imidazo[1,2-b]pyrazoles has been developed from N-(2-bromoaryl)-thioacetanilides. A series of benzo[4,5]imidazo[1,2-b]pyrazoles were obtained in excellent yields with CuI/heterocyclic ketene aminals catalytic system in the presence of Cs_2CO_3 in dimethyl sulfoxide(DMSO) at 120 ℃ within 10 min. The reaction provides an fast and efficient protocol to access a series of benzo[...
*Corresponding author.E-mail:wenlirong@qust.edu.cnReceived December 7,2016;revised January 20,2017;published online February 8,2017.Project supported by the National Natural Science Foundation of China(Nos.21572110,21372137)and the Natural Science Foundat