K2S2O8-Mediated halogenation of 2-arylimidazo[1,2-a]pyridines using sodium halides as the halogen sources
作者:Praewpan Katrun、Chutima Kuhakarn
DOI:10.1016/j.tetlet.2019.03.008
日期:2019.4
halogenation of 2-arylimidazo[1,2-a]pyridines using sodium chloride/bromide/iodide as the halogen sources in the presence of K2S2O8 as an easy-to-handle oxidizing agent was developed. The present work offers an efficient and rapid access to 3-chloro-, 3-bromo- and 3-iodo-2-arylimidazo[1,2-a]pyridines which can be readily converted to C3-substituted imidazo[1,2-a]pyridines by cross-coupling reactions.
开发了在K 2 S 2 O 8作为易于处理的氧化剂存在下,使用氯化钠/溴化物/碘化物作为卤素源,方便地卤化2-芳基咪唑并[1,2- a ]吡啶的方法。本工作提供了一种快速有效地获得3-氯-,3-溴-和3-碘-2-芳基咪唑并[1,2- a ]吡啶的方法,这些吡啶基很容易转化为C 3取代的咪唑并[1,2] -一个]吡啶通过交叉偶联反应。
Synergy of Anodic Oxidation and Cathodic Reduction Leads to Electrochemical C—H Halogenation
作者:Zhilin Zhou、Yong Yuan、Yangmin Cao、Jin Qiao、Anjin Yao、Jing Zhao、Wanqing Zuo、Wenjie Chen、Aiwen Lei
DOI:10.1002/cjoc.201900091
日期:2019.6
We herein uncovered an electrochemical C—Hhalogenation protocol that synergistically combines anodic oxidation and cathodic reduction for C—X bond formation. The reaction was demonstrated under exogenous‐oxidant‐free conditions. Moreover, this is the first example of activating CBr4, CHBr3, and CCl3Br under electrochemical conditions.
Ultrasound-Promoted and Base-Mediated Regioselective Bromination of Imidazo[1,2-a]pyridines with Pyridinium Tribromide
作者:Qing-Wen Gui、Hongmei Jiang、Dingyi Guo、Yixin Zhang、Qin-Peng Shen、Shiyun Tang、Junheng You、Yi Huo、Huixian Wang
DOI:10.1055/s-0040-1707856
日期:2020.9
Abstract By using pyridinium tribromide as the bromo source, an efficient and practical protocol for the synthesis of C3-brominated imidazo[1,2-a]pyridines through ultrasound-promoted and Na2CO3-mediated regioselective bromination of imidazo[1,2-a]pyridines has been developed. This method effectively avoids the use of metal catalysts and harsh reaction conditions, and shows attractive characteristics
摘要 通过使用三溴化吡啶鎓作为溴源,通过超声促进和Na 2 CO 3介导的咪唑并[1,2-]区域选择性溴化合成C3-溴化的咪唑并[1,2- a ]吡啶的有效而实用的方案。已经开发了α ]吡啶。该方法有效地避免了使用金属催化剂和苛刻的反应条件,并显示出引人注目的特性,例如操作简便,宽范围的基材范围以及良好至优异的收率,易于规模化生产和高能源效率。
Hypervalent Iodine Mediated Efficient Solvent-Free Regioselective Halogenation and Thiocyanation of Fused N-Heterocycles
作者:Divakar Reddy Indukuri、Gal Reddy Potuganti、Manjula Alla
DOI:10.1055/s-0037-1611856
日期:2019.8
2-a]pyridine/pyrimidine heterocycles has been achieved under solvent-free reaction conditions. Halogenations and thiocyanation of the heterocycles could be accomplished by simple grinding of reactants and hypervalent iodine reagents with the corresponding alkali metal or ammonium salts. The method has been extrapolated to a cleaner synthesis of brominated imidazo[1,2-a]pyridine/pyrimidine derivatives
N-(Pyridin-2-yl)amides and 3-bromoimidazo[1,2-a]pyridines were synthesized respectively from α-bromoketones and 2-aminopyridine under different reaction conditions. N-(Pyridin-2-yl)amides were formed in toluene via C–C bond cleavage promoted by I2 and TBHP and the reaction conditions were mild and metal-free. Whereas 3-bromoimidazopyridines were obtained in ethyl acetate via one-pot tandem cyclization/bromination
以α-溴酮和2-氨基吡啶在不同反应条件下分别合成N- (吡啶-2-基)酰胺和3-溴咪唑并[1,2- a ]吡啶。N- (Pyridin-2-yl)amides 在甲苯中通过I 2和 TBHP促进的 C-C 键断裂形成,反应条件温和且不含金属。3-溴咪唑并吡啶在乙酸乙酯中通过一锅串联环化/溴化仅加入TBHP得到,而进一步溴化促进环化形成咪唑并吡啶,不需要碱,多功能的3-溴咪唑并吡啶可以进一步转移到其他骷髅。