(Diacetoxy)iodobenzene-Mediated Regioselective Imidation of Imidazoheterocycles with N‑Fluorobenzenesulfonimide

Metal-free (diacetoxy)­iodobenzene-mediated regioselective imidation of imidazoheterocycles using commercially available N-fluorobenzenesulfonimide as an imidating reagent has been developed. This protocol exhibits broad substrate scope with good to excellent yields of the imidated imidazopyridines under mild conditions in short reaction times. The present protocol also represents an efficient way to access the imidated derivatives of imidazo­[2,1-b]­thiazole, benzo­[d]­imidazo-[2,1-b]­thiazole, indoles, and indolizines. A radical mechanistic pathway has been proposed for the present protocol.本研究开发了一种以市售N-氟代苯磺酰亚胺（N-fluorobenzenesulfonimide）作为亚胺化试剂，在无金属二醋酸碘苯((diacetoxy)iodobenzene)介导下实现咪唑并杂环区域选择性亚胺化的合成策略。该方法底物适用范围宽泛，在温和反应条件下以较短反应时间即可获得良好至优异的亚胺化咪唑并吡啶类产物产率。本方案同样可高效制备咪唑并[2,1-b]噻唑、苯并[d]咪唑并[2,1-b]噻唑、吲哚类及中氮茚类的亚胺化衍生物。针对该反应体系，本研究提出了自由基反应机理。