Yi Fengping, Fu Chao, Sun Qihui, Wei Huazhen, Yu Genfa, Yi Weiyin
School of Perfume and Aroma Technology, Shanghai Institute of Technology Shanghai 201418 P. R. China
RSC Adv. 2019 Dec 19;9(72):42172-42182. doi: 10.1039/c9ra09265j. eCollection 2019 Dec 18.
A facile transition-metal-free protocol to form 2-iminoimidazo[1, 2-]-pyridines bearing a -CHBr group and an aza-quaternary carbon center at the 3 position from -(2-pyridyl)amidines substrates, in which the new heterocyclic skeletons constructed from amidines radical reactions or nucleophilic substitution reactions are promoted only by CBr under mild conditions, is demonstrated. The reactions were realized by intramolecular CDC reaction involving C-N and C-C bond formation the sequential C(sp)-H bifunctionalization mode on the same carbon atom under mild conditions. Moreover, this work also provides an excellent and representative example for CBr as an efficient reagent to initiate radical reactions under initiator-free conditions or to give rise to nucleophilic substitution reactions only by base.
展示了一种简便的无过渡金属方法，可从-(2-吡啶基)脒底物形成在3位带有-CHBr基团和氮杂季碳中心的2-亚氨基咪唑并[1,2-]吡啶，其中由脒自由基反应或亲核取代反应构建的新杂环骨架在温和条件下仅由CBr促进。这些反应通过涉及C-N和C-C键形成的分子内CDC反应在温和条件下在同一碳原子上以连续的C(sp)-H双功能化模式实现。此外，这项工作还提供了一个出色的代表性例子，说明CBr作为一种有效的试剂，可在无引发剂条件下引发自由基反应或仅通过碱引发亲核取代反应。
