Parallelism Between Nucleophilically Solvent-Assisted and Phenyl-Assisted Reactions. Possible Existence of Nucleophilically ?-Phenyl-Solvated Ion Pairs
necessarily originate from a cationic species are the most abundant ones. It is suggested that these reactions could proceed through ion-pairintermediates, which are nucleophilically solvated by phelyl or by the solvent. A parallel between phenyl assistance and ‘SN2 (intermediate)’ mechanism, suggested by Bentely & Schleyer, is drawn.
比较了两个环烷基系统的β-甲基和β-苯基衍生物在M e OH和t- BuOh中的溶剂分解速率常数。看来β-苯基衍生物以与β-甲基衍生物相同的速率溶解。缺乏减速归因于苯的协助。通过对反应产物的构型分析确定,那些必然源自阳离子物种的产物是最丰富的那些。建议这些反应可以通过离子对中间体进行,该离子对中间体被苯基或溶剂亲核溶剂化。Bentely&Schleyer建议在苯助剂和“ S N 2(中间体)”机理之间建立一个平行关系。
Assistance d'un groupe voisin pour des tosylates secondaires β substitues diequatoriaux dans l'hexafluoroisopropanol 97%
作者:J. Laureillard、E. Casadevall
DOI:10.1016/s0040-4020(01)88454-4
日期:1984.1
Solvolysis rates in methanol and 97% hexafluoroisopropanol (HFIP) for four β-methyl and β-phenyl bicyclic tosylates, show that solventnucleophilicassistance is operating in the former solvent. However, in 97% HFIP, for three of the mentioned compounds, the mechanism involves π or σ neighboring group assistance. The factors influencing the occurrence of these processes are discussed. Owing to these
β-甲基和β-苯基四环甲苯磺酸盐在甲醇和97%六氟异丙醇(HFIP)中的溶剂分解速率表明,溶剂亲核助剂正在前一种溶剂中运行。但是,在97%的HFIP中,对于上述三个化合物,该机理涉及π或σ邻基团辅助。讨论了影响这些过程发生的因素。由于在用于获得k c参考机理的非亲核溶剂中存在这些可能的邻近基团辅助作用,因此得出结论,必须谨慎使用提议作为溶剂亲核助剂的定量评估方法的k a / k c比值。
Condensation of Thienylcycloalkenes with Maleic Anhydride<sup>1</sup>
作者:Jacob Szmuszkovicz、Edward J. Modest
DOI:10.1021/ja01157a145
日期:1950.1
Conformational study of phenethylamine receptor sites. 2. Synthesis of dl-2-amino-3-phenyl-trans-decalins and dl-2-isopropylamino-3-phenyl-trans-decalins
作者:Edward E. Smissman、Thomas L. Pazdernik
DOI:10.1021/jm00259a006
日期:1973.1
A conformational study of .beta.-phenethanolamine receptor sites. I. The syntheses of the 3-amino-2-phenyl-trans-2-decalols