The influence of steric effects on the kinetics and mechanism of S<sub>N</sub>Ar reactions of 1-phenoxy-nitrobenzenes with aliphatic primary amines in acetonitrile
作者:Chukwuemeka Isanbor
DOI:10.1002/poc.3687
日期:2017.11
be mediated by reduced steric congestion around the reaction centre. Specific steric effects, leading to rate retardation, are noted for the ortho‐CF3 group. In general, reactant‐bearing ortho‐CF3 group were subject to base catalysis irrespective of the amine nucleophile and values of kAm/k−1 are reduced as the size of the amine get bulkier. This is likely to reflect increases in values of k−1 coupled
速率常数报道的1-苯氧基二硝基苯,反应3,1-苯氧基dinitrotrifluoromethylbenzenes,4,与Ñ丙胺,和乙腈作为溶剂1- methylheptylamine。将结果与先前报道的正丁胺,吡咯烷和哌啶的结果进行比较。减少的环活化导致亲核攻击的k 1值较低,尽管这可能是由于反应中心周围的空间拥塞减少所引起的。对于邻-CF 3组,存在导致速率减慢的特定空间效应。通常,含反应物的邻CF 3不论胺亲核试剂如何,组均进行碱催化,并且随着胺的体积变大,k Am / k -1的值减小。这可能反映出k -1值的增加以及k Am值的减小,因为从两性离子中间体到催化胺的质子转移在热力学上变得不太有利。
Kinetics of S<sub>N</sub>Ar reactions of 1-phenoxy-nitrobenzenes with aliphatic amines in toluene: ring substituent and solvent effects on reaction pathways
Diverse and chemoselective sigmatropic shift rearrangements of multisubstituted <i>N</i>,<i>O</i>-diarylhydroxylamines
作者:Guangyu Zhang、Simin Sun、Shili Hou、Jiaxi Xu
DOI:10.1039/d2ob00771a
日期:——
tandem Smiles rearrangement and amide/ester exchange reactions, generating 2-arylaminoaryl benzoate derivatives. N-Phenyl-O-(2,4,6-trinitrophenyl)hydroxylamines undergo tandem double O[1,3] sigmatropic shift rearrangement to produce formal O[1,5] shift products. However, O-(2,6-dinitrophenyl)-N-(4-substituted phenyl)hydroxylamines undergo tandem O[1,3] and double [3,3] sigmatropic shift rearrangements
N , O-二芳基羟胺通常有利于[3,3] σ迁移重排。使用合理设计的底物对多取代的N , O-二芳基羟胺可能的 N/O[1,3] σ 迁移重排进行了实验研究,这些底物通常由合适的硝基芳基卤化物和N-芳基羟胺通过芳族亲核取代原位制备。结果表明,N - 和O -(2,4,6-三甲基苯基)羟胺仍然有利于 [3,3] σ 位移,然后是互变异构,而不是 N[1,3] 和 O[1,3] σ 位移和N的重排产物-(2,4,6-三甲基苯基)羟胺进一步进行分子内亲核加成得到二苯并[ b , d ]呋喃-4a(9b H )-胺衍生物,而N- (4-单-和3,5-二取代苯基) -O- (2,4,6-三硝基苯基)羟胺有利地首先经历O[1,3] σ迁移,然后进行串联Smiles重排和酰胺/酯交换反应,生成2-芳基氨基芳基苯甲酸酯衍生物。N -Phenyl - O -(2,4,6-三硝基苯基)羟胺经历串联双 O[1