16714-06-0Relevant articles and documents
Oligoethylene glycols as highly efficient mutifunctional promoters for nucleophilic-substitution reactions
Jadhav, Vinod H.,Jang, Seung Ho,Jeong, Hwan-Jeong,Lim, Seok Tae,Sohn, Myung-Hee,Kim, Ju-Young,Lee, Sungyul,Lee, Ji Woong,Song, Choong Eui,Kim, Dong Wook
, p. 3918 - 3924 (2012)
Herein, we report the promising use of n-oligoethylene glycols (oligoEGs) as mutifunctional promoters for nucleophilic-substitution reactions employing alkali metal salts. Among the various oligoEGs tested, pentaethylene glycol (pentaEG) had the most efficient catalytic activity. In particular, when compared with 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 of the pentaEG promoter. All of these reactions provided their desired products in excellent yields. Furthermore, the combination of pentaEG and a tert-alcohol medium showed tremendous efficiency in the nucleophilic-displacement reactions (fluorination and methoxylation) of base-sensitive substrates with basic nucleophiles (cesium fluoride and potassium methoxide, respectively). The catalytic role of oligoEGs was examined by quantum-chemical methods. The oxygen atoms in oligoEGs were found to act as Lewis bases on the metal cations to produce the "flexible" nucleophile, whereas the two terminal hydroxy (OH) groups acted as "anchors" to orientate the nucleophile and the substrate into an ideal configuration for the reaction. The EG race: OligoEGs, such as pentaethylene glycol (pentaEG), act as mutifunctional promoters for nucleophilic-substitution reactions with the corresponding alkali-metal salts. The combination of pentaEG and a tert-alcohol media system showed tremendous efficiency in the fluorination and methoxylation of base-sensitive substrates by using the corresponding basic nucleophiles (see figure). Copyright
Organocatalysis of nucleophilic substitution reactions by the combined effects of two promoters fused in a molecule: Oligoethylene glycol substituted imidazolium salts
Jadhav, Vinod H.,Kim, Ju-Young,Chi, Dae Yoon,Lee, Sungyul,Kim, Dong Wook
, p. 533 - 542 (2014)
Oligoethylene glycol substituted imidazolium salts were synthesized as promoters for a range of SN2 reactions, and their efficiency was examined. These tailor-made organic promoters enhanced the nucleophilicity of alkali metal salts significantly through the combined effects of two promoters (oligoethylene glycols and imidazolium salts) in a single molecule. The effects of the oligoethylene glycol side chain length, ionic liquid anions, nucleophiles, and substrates were investigated systematically. [hexaEGmim][OMs] and [dihexaEGim][OMs] showed the highest efficiency for SN2 reactions using alkali metal salts. The role of the terminal hydroxyl groups of the oligoethylene glycol moiety was assessed by examining the relative S N2 yields of chlorination and bromination. The results showed that the hydrogen bonding strength of the hydroxyl groups with the nucleophile is very important. The mechanism for the excellent promotion of SN2 reactions by oligoEGILs was examined by quantum chemical calculations. The results showed that the oxygen atoms in the oligoethylene glycol portion and the ionic liquid anion act on the counter cation K+ or Na+ as a Lewis base, to enhance the reactivity of the metal salts significantly.
Synthesis and membranoprotective properties of new disulfides with monoterpene and carbohydrate fragments
Pestova,Izmestev,Shevchenko,Rubtsova,Kuchin
, p. 723 - 731 (2015/11/27)
A cooxidation of carbohydrate and terpene thiols gives mixtures of disulfides containing 51 - 90% of the unsymmetric product. Membranoprotective and antioxidant properties of obtained unsymmetric and symmetric disulfides were evaluated based on their ability to inhibit the H2O2-induced hemolysis of erythrocytes, as well as the accumulation of secondary products of the peroxy oxidation of lipids and the oxidation of hemoglobin.