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。
Direct, Metal-free C(sp<sup>2</sup>
)−H Chalcogenation of Indoles and Imidazopyridines with Dichalcogenides Catalysed by KIO<sub>3</sub>
作者:Jamal Rafique、Sumbal Saba、Marcelo S. Franco、Luana Bettanin、Alex R. Schneider、Lais T. Silva、Antonio L. Braga
DOI:10.1002/chem.201705404
日期:2018.3.15
synthesis of 3‐Se/S‐indoles and imidazo[1,2‐a]pyridines through direct C(sp2)−H bond chalcogenation of heteroarenes with half molar equivalents of different dichalcogenides, using KIO3 as a non‐toxic, easy‐to‐handle catalyst and a stoichiometric amount of glycerol. The reaction features are high yields, based on atom economy, easy performance on gram‐scale, metal‐ and solvent‐free conditions as well as applicability
本文中,我们报告了一种更环保的协议,该方法通过杂芳烃的直接C(sp 2)-H键硫代半数当量的不同二硫代半乳糖苷合成3-Se / S-吲哚和咪唑并[1,2- a ]吡啶KIO 3是一种无毒,易于操作的催化剂和化学计量的甘油。该反应的特征是基于原子经济性的高收率,在克级,无金属和无溶剂条件下易于操作以及适用于不同类型的N-杂芳烃。
Iodine–triphenylphosphine mediated sulfenylation of imidazoheterocycles with sodium sulfinates
作者:Xuhu Huang、Shucheng Wang、Bowen Li、Xin Wang、Zemei Ge、Runtao Li
DOI:10.1039/c4ra17237j
日期:——
An efficient approach to sulfenyl imidazoheterocycles has been developed via iodine–triphenylphosphine mediated direct sulfenylation of imidazoheterocycles with sodiumsulfinates. The reactions proceed smoothly under transition-metal-free conditions with a broad range of substrate scope, giving the desired products in moderate to excellent yields.
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.