Imidazolium-containing diselenides for catalytic oxidations with hydrogen peroxide and sodium bromide in aqueous solutions
作者:Eduardo E. Alberto、Antonio L. Braga、Michael R. Detty
DOI:10.1016/j.tet.2012.08.004
日期:2012.12
The design and synthesis of imidazolium-containing diselenides 4a–c is described. The introduction of the N-methylimidazolium group gives freely soluble compounds in water, unlike the majority of common organic diselenides. Catalytic amounts of 4a–c effectively promote bromination of organic substrates using a safe and inexpensive NaBr/H2O2 system in water. Kinetics experiments revealed that the bromination
描述了含咪唑鎓二硒化物4a – c的设计与合成。与大多数常见的有机二硒化物不同,N-甲基咪唑鎓基团的引入可在水中提供可自由溶解的化合物。使用安全和廉价的NaBr / H 2 O 2水溶液,催化量的4a – c可有效促进有机底物的溴化。动力学实验表明,4-戊烯酸的溴化反应对NaBr和H 2 O 2都具有一级依赖性浓度反应速率也对溶液的pH敏感。制备反应表明,与4a相比,二苯基二硒化物5是不良的催化剂,离子液体溴化1-苄基-3-甲基咪唑鎓溴化物6没有与H 2 O 2的催化活性,表明结合的官能团具有协同作用。
Hydrogen‐Bond‐Donor Solvents Enable Catalyst‐Free (Radio)‐Halogenation and Deuteration of Organoborons
A hydrogenbonddonorsolvent assisted (radio)halogenation and deuteration of organoborons has been developed. The reactions exhibited high functional group tolerance and needed only an ambient atmosphere. Most importantly, compared to literature methods, our conditions are more consistent with the principals of green chemistry (e.g., metal‐free, strong oxidant‐free, more straightforward conditions)
reactions are practical and environmentally benign one-pot methods for the preparation of aromatic nitriles, cinnamonitriles, and aliphatic nitriles from aryl bromides, β-bromostyrenes, and alkyl bromides, respectively, through the formation of Grignardreagents and their DMF or N-formylpiperidine adducts.