Regioselective, Solvent- and Metal-Free Chalcogenation of Imidazo[1,2-<i>a</i>
]pyridines by Employing I<sub>2</sub>
/DMSO as the Catalytic Oxidation System
作者:Jamal Rafique、Sumbal Saba、Alisson R. Rosário、Antonio L. Braga
DOI:10.1002/chem.201600800
日期:2016.8.8
molecular‐iodine‐catalyzed chalcogenations (S and Se) of imidazo[1,2‐a]pyridines were achieved by using diorganoyl dichalcogenides undersolvent‐freeconditions. This approach afforded the desired products that had been chalcogenated regioselectively at the C3 position in up to 96 % yield by using DMSO as an oxidant, in the absence of a metal catalyst, and under an inert atmosphere. This mild, green approach allowed
通过在无溶剂条件下使用二有机基二卤化氢实现咪唑并[1,2- a ]吡啶的高效分子碘催化硫属元素化(S和Se)。通过使用DMSO作为氧化剂,在没有金属催化剂的情况下,并且在惰性气氛下,该方法提供了所需的产物,该产物已经在C3位置进行了区域硫磺化,产率高达96%。这种温和的绿色方法可以制备具有结构多样性的不同类型的硫族化咪唑并[1,2- a ]吡啶。此外,当前协议还扩展到其他N杂环核。
An efficient and clean CuI-catalyzed chalcogenylation of aromatic azaheterocycles with dichalcogenides
作者:Zhen Li、Jianquan Hong、Xigeng Zhou
DOI:10.1016/j.tet.2011.03.067
日期:2011.5
A highly efficient and environmentally friendly method for catalytic chalcogenylation of imidazopyridines, imidazopyrimidines, indoles, and pyrrolo[2,3-b]pyridines with dichalcogenides has been developed by using CuI as catalyst under air. The reactions proceed smoothly to give the desired products in moderate to excellent yields, without the presence of other additive.
通过在空气中使用CuI作为催化剂,开发了一种高效的,环境友好的方法,该方法用于用二硫代甲烷催化咪唑并吡啶,咪唑并嘧啶,吲哚和吡咯并[2,3- b ]吡啶。反应平稳进行,以中等至优异的产率得到所需产物,而没有其他添加剂的存在。
NH4I-catalyzed chalcogen(S/Se)-functionalization of 5-membered N-heteroaryls under metal-free conditions
作者:Luana Bettanin、Sumbal Saba、Carlos V. Doerner、Marcelo S. Franco、Marcelo Godoi、Jamal Rafique、Antonio L. Braga
DOI:10.1016/j.tet.2018.05.084
日期:2018.7
Herein, we described the NH4I-catalyzed C-H bond chalcogenation of N-heteroaryls in the presence of a minimum amount of DMSO/H2O/acetic acid as additives (2.5/2.5/1 M equiv., respectively), under metal-free conditions. Under optimized conditions, a wide variety of sulfenyl/selenyl imidazo[1,2-alpha]pyridines were prepared in very good yields. Moreover, the present approach was also highly efficient for the chalcogenation of different 5-membered N-heteroaryls, e.g., indole, imidazothiazole, indazole and imidazopyrimidine derivatives. (C) 2018 Elsevier Ltd. All rights reserved.