Syntheses of 1,3-bis(1'-alkylpyridinium)cyclopentadienides and the x-ray crystal structures of 1,3-bis(1'-methyl-2'-pyridinium)indenide bromide and 1-(1'-methyl-2'-pyridinium)-3-(1"-methyl-4''-pyridinium)cyclopentadienide bromide
Reactivity in the nucleophilic aromatic substitution reactions of pyridinium ions
作者:Jeannette T. Bowler、Freeman M. Wong、Scott Gronert、James R. Keeffe、Weiming Wu
DOI:10.1039/c4ob00946k
日期:——
The “element effect” in nucleophilicaromaticsubstitution reactions (SNAr) is characterized by the leaving group order, L = F > NO2 > Cl ≈ Br > I, in activated aryl substrates. A different leaving group order is observed in the substitution reactions of ring-substituted N-methylpyridinium compounds with piperidine in methanol: 2-CN ≥ 4-CN > 2-F ∼ 2-Cl ∼ 2-Br ∼ 2-I. The reactions are second-order in
亲核芳香族取代反应 (S N Ar) 中的“元素效应”以离去基团顺序为特征,L = F > NO 2 > Cl ≈ Br > I,在活化的芳基底物中。在环取代的N的取代反应中观察到不同的离去基团顺序-甲基吡啶鎓化合物与哌啶的甲醇溶液:2-CN ≥ 4-CN > 2-F ∼ 2-Cl ∼ 2-Br ∼ 2-I。[哌啶]中的反应是二级反应,其机制涉及确定哌啶和底物-哌啶加成中间体之间氢键形成的速率,然后该中间体去质子化。计算结果表明,氢键复合物的去质子化可能是无障碍的,并且伴随着 L = Cl、Br 和 I 的离去基团 (E2) 同时丢失,但随后离去基团迅速丢失( E1cB-like) 对于较差的离去基团 CN 和 F。2-和 4-氰基底物的反应性提高了大约 50 倍,这归因于去质子化步骤中吸电子氰基的影响。
[EN] PENTAVALENT SYNTHESIS OF OLIGONUCLEOTIDES CONTAINING STEREOSPECIFIC ALKYLPHOSPHONATES AND ARYLPHOSPHONATES<br/>[FR] SYNTHESE PENTAVALENTE D'OLIGONUCLEOTIDES CONTENANT DES ALKYLPHOSPHONATES ET DES ARYLPHOSPHONATES STEREOSPECIFIQUES
申请人:——
公开号:WO1994000473A2
公开(公告)日:1994-01-06
[EN] The present invention provides a method for making R stereospecific alkyl- and aryl-phosphonate linkages between nucleotides. These methods can be used for automated synthesis of oligonucleotides having sequential R stereospecific alkyl- and aryl-phosphonate linkages. The present invention is also directed to the oligonucleotides having several sequential R phosphonate linkages which were produced by the subject methods. Moreover, the present invention provides methods for using the subject oligonucleotides, including methods for regulating the biosynthesis of a DNA, an RNA or a protein and methods for detecting and isolating complementary nucleic acid targets. [FR] Procédé de production de liaisons R stéréospécifiques alkyl- et aryl-phosphonate entre des nucléotides. On peut utiliser ce procédé dans la synthèse automatique d'oligonucléotides présentant des liaisons séquentielles R alkyl- et aryl-phoshonates stéréospécifiques. L'invention concerne également les oligonucléotides présentant plusieurs liaisons R phosphonate séquentielles produites selon les procédés de l'invention. De plus, l'invention a trait à des procédés d'utilisation des oligonucléotides de l'invention, y compris des procédés de régulation de la biosynthèse d'un ADN, d'un ARN ou d'une protéine, ainsi qu'à des procédés de détection et d'isolement d'acides nucléiques complémentaires cibles.
Micellar effects upon the reaction of hydroxide ion with N-alkyl-2-bromopyridinium ion
作者:Hamad A. Al-Lohedan、Clifford A. Bunton、Laurence S. Romsted
DOI:10.1021/jo00139a029
日期:1982.8
Syntheses of 1,3-bis(1'-alkylpyridinium)cyclopentadienides and the x-ray crystal structures of 1,3-bis(1'-methyl-2'-pyridinium)indenide bromide and 1-(1'-methyl-2'-pyridinium)-3-(1"-methyl-4''-pyridinium)cyclopentadienide bromide