建立了一种快速、高效的CuI催化N-(2-溴芳基)-5-苯基-1H-吡唑-3-胺发生分子内C—N偶联反应合成苯并[4,5]咪唑并[1,2-b]吡唑衍生物的新方法.该方法以廉价的CuI/杂环烯酮缩胺为催化剂,在二甲基亚砜(DMSO)中反应只需10min,具有反应迅速、操作简便、合成效率高等优点.
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[4,5]imidazo[1,2-b]pyrazoles in good to high yields.