Ben El Ayouchia Hicham, Bahsis Lahoucine, Anane Hafid, Domingo Luis R, Stiriba Salah-Eddine
Laboratoire de Chimie Analytique et Moléculaire, LCAM, Faculté Polydisciplinaire de Safi, Université Cadi Ayyad Safi 46030 Morocco
Departamento de Química Orgánica, Universidad de Valencia Avda. Dr Moliner 50, 46100 Burjassot Valencia Spain.
RSC Adv. 2018 Feb 16;8(14):7670-7678. doi: 10.1039/c7ra10653j. eCollection 2018 Feb 14.
The copper(i) catalyzed azide-alkyne [3 + 2] cycloaddition (32CA) reaction and its uncatalyzed version have been studied for systematic understanding of this relevant organic transformation, using DFT calculations at the B3LYP/6-31G(d) (LANL2DZ for Cu) computational levels. In the absence of a copper(i) catalyst, two regioisomeric reaction paths were studied, indicating that the 32CA reaction takes place through an asynchronous one-step mechanism with a very low polar character. The two reactive channels leading to 1,4- and 1,5-regisomer present similar high activation energies of 18.84 and 18.51 kcal mol, respectively. The coordination of copper(i) to alkyne produces relevant changes in this 32CA reaction. Analysis of the global and local electrophilicity/nucleophilicity allows explaining correctly the behaviors of the copper(i) catalyzed cycloaddition. Coordination of the copper to alkyne changes the mechanism from a non-polar one-step mechanism to a polar stepwise one, as a consequence of the high nucleophilic character of the dinuclear Cu(i)-acetylide complex. Parr and Fukui functions and Dual Descriptor correctly explain the observed regioselectivity by means of the most favorable two-center interaction that takes place along the 1,4 reaction path.
使用B3LYP/6 - 31G(d)（铜采用LANL2DZ）计算水平的密度泛函理论（DFT）计算，对铜（I）催化的叠氮化物 - 炔烃[3 + 2]环加成（32CA）反应及其无催化版本进行了研究，以系统地理解这种相关的有机转化。在没有铜（I）催化剂的情况下，研究了两条区域异构反应路径，结果表明32CA反应通过具有极低极性特征的非同步一步机理进行。导致1,4 - 和1,5 - 区域异构体的两条反应通道分别具有相似的高活化能，即18.84和18.51千卡/摩尔。铜（I）与炔烃的配位在该32CA反应中产生了相关变化。对全局和局部亲电性/亲核性的分析能够正确解释铜（I）催化环加成的行为。由于双核Cu（I） - 乙炔化物配合物的高亲核性，铜与炔烃的配位将机理从非极性一步机理转变为极性分步机理。帕尔和福井函数以及双描述符通过沿1,4反应路径发生的最有利的两中心相互作用，正确地解释了观察到的区域选择性。
