合成了低聚乙二醇取代的咪唑鎓盐作为一系列S N 2反应的促进剂,并检查了它们的效率。这些量身定制的有机促进剂通过两个促进剂(低聚乙二醇和咪唑鎓盐)在单个分子中的联合作用,显着增强了碱金属盐的亲核性。系统研究了低聚乙二醇侧链长度,离子液体阴离子,亲核试剂和底物的影响。[hexaEGmim] [OMs]和[dihexaEGim] [OMs]显示了使用碱金属盐进行S N 2反应的最高效率。通过检查相对S N来评估低聚乙二醇部分的末端羟基基团的作用2氯化和溴化收率。结果表明,羟基与亲核试剂的氢键强度非常重要。通过量子化学计算研究了oligoEGILs促进S N 2反应的优异机理。结果表明,低聚乙二醇部分中的氧原子和离子液体阴离子作为路易斯碱作用于抗衡阳离子K +或Na +上,从而显着提高了金属盐的反应性。
Bis-Terminal Hydroxy Polyethers as All-Purpose, Multifunctional Organic Promoters: A Mechanistic Investigation and Applications
作者:Ji Woong Lee、Hailong Yan、Hyeong Bin Jang、Hong Ki Kim、Sung-Woo Park、Sungyul Lee、Dae Yoon Chi、Choong Eui Song
DOI:10.1002/anie.200903903
日期:2009.9.28
Achiral polyether derivatives have been shown to dramatically accelerate SN2 reactions by the simultaneous activation of both the nucleophile (KF) and electrophile (sulfonate; see picture). By using chiral variants as catalysts, the desilylative kinetic resolution of the silyl ethers of racemic secondary alcohols has been achieved. Density functional calculations provide detailed insight into the modes
已显示非手性聚醚衍生物可通过亲核试剂(KF)和亲电试剂(磺酸盐;见图)的同时活化来显着加速S N 2反应。通过使用手性变体作为催化剂,已获得外消旋仲醇的甲硅烷基醚的脱甲硅烷基的动力学拆分。密度泛函计算可深入了解此类有机促进剂的作用方式。
Oligoethylene Glycols as Highly Efficient Mutifunctional Promoters for Nucleophilic-Substitution Reactions
作者:Vinod H. Jadhav、Seung Ho Jang、Hwan-Jeong Jeong、Seok Tae Lim、Myung-Hee Sohn、Ju-Young Kim、Sungyul Lee、Ji Woong Lee、Choong Eui Song、Dong Wook Kim
DOI:10.1002/chem.201102455
日期:2012.3.26
other nucleophiles examined, a fluorine nucleophile generated from CsF was significantly activated by the pentaEG promoter. We also performed various facile nucleophilic‐displacement reactions, such as the halogenation, acetoxylation, thioacetoxylation, nitrilation, and azidation of various substrates with potassium halides, acetate, thioacetate, cyanide, and sodium azide, respectively, in the presence
Synthesis of plant-growth regulators. Part III. ω-2-Naphthyloxyalkanecarboxylic acids
作者:P. M. Pope、D. Woodcock
DOI:10.1039/jr9540001721
日期:——
Polymer-supported oligoethylene glycols as heterogeneous multifunctional catalysts for nucleophilic substitution
作者:Vinod H. Jadhav、Hwan-Jeong Jeong、Seok Tae Lim、Myung-Hee Sohn、Choong Eui Song、Dong Wook Kim
DOI:10.1016/j.tet.2013.02.044
日期:2013.4
We investigated various structurally modified polystyrene-supported oligoethylene glycols (PSoligoEG) in order to find an optimized PSoligoEG by examining the dependence of their catalytic activity on the oligoethylene glycol chain length and the loading level of the oligoethylene glycol portion on the polystyrene support. From this, we found that the PSpentaEG with the highest pentaEG loading had the best catalytic efficacy among the various PSoligoEGs in nucleophilic substitutions. This PSpentaEG absorbed both polar aprotic solvents, such as DMSO, DMF, and acetonitrile, as well as protic media, such as tert-amyl alcohol and aqueous acetone, and swelled considerably. To expand the scope of the PSpentaEG as a heterogeneous catalyst for diverse nucleophilic displacement reactions, we carried out the thioacetoxylation, nitrilation, azidation, iodination, bromination, chlorination, and methoxylation using the corresponding alkali metal salts in the presence of PSpentaEG in various solvents; all the reactions proceeded smoothly, affording the corresponding products in high yields. (C) 2013 Elsevier Ltd. All rights reserved.