Crossing the threshold from accelerated substitution to elimination with a bifunctional macrocycle
作者:Jeremiah J. Gassensmith、Jung-Jae Lee、Bruce C. Noll、Bradley D. Smith
DOI:10.1039/b719658j
日期:——
binding amide residues can be N-alkylated at highly accelerated reaction rates to give quaternary ammonium products. This present study examines the reactivity with 1,2-disubstituted ethanes. Accelerated substitution is observed with 1,2-dichloroethane (5000 times faster than analogous control amines); whereas, accelerated elimination is the outcome with 3-halopropionitriles (10000 times faster than
先前报道的大环胺与 阴离子结合 酰胺 残留物可以以高度加速的反应速率进行N-烷基化,得到季铵盐 铵盐产品。本研究研究了与1,2-二取代乙烷的反应性。观察到加速取代1,2-二氯乙烷(比类似的对照胺快5000倍); 然而,3-卤代丙腈的结果是加速消除(比类似的对照胺快1万倍)。质子化形式的结构大循环 被分析 X射线衍射。的消除率3-氯, 3-溴 和 3-碘丙腈 进行测量,并求出二阶速率常数的相对阶 三乙胺 是1:43:182,反映了预期的离开顺序 团体能力。在这种情况下大循环,二阶速率常数的相对阶为1:29:61。 氯−离开团体。动力学数据与双分子一致的SYN淘汰机制。