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首页> 外文期刊>RSC Advances >Competing mechanisms for the reaction of dichloropropynylborane with 2-tert-butylbutadiene. Diels-Alder reaction versus alkynylboration
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Competing mechanisms for the reaction of dichloropropynylborane with 2-tert-butylbutadiene. Diels-Alder reaction versus alkynylboration

机译：二氯丙炔酰基与2-叔丁基丁二烯反应的竞争机制。 Diels-Alder反应与炔硼硼酸盐

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摘要

Density functional theory and the quantum theory of atoms in molecules approach were used to study two competing process: the Diels-Alder reaction (DA) and the 1,4-alkynylboration (AB) between dichloropropynylborane (1) and 2-tert-butylbutadiene (2) in dichloromethane. We analyzed several reaction pathways related with such reactions for both orientations (meta and para). The stepwise mechanisms for the two competitive reactions share the first step that leads to an intermediate zwitterionic structure. The second step is more favorable for the reaction occurring via TSC-m that leads to the meta enyne product 5, which is the kinetic product. The formation of the meta DA product cannot be explained through a direct cycloaddition, due to the higher activation free energy of the associated transition structure (TSB-m). An alternative transition structure with [4 + 3] character (TSD-m) that connects the meta enyne 5 with the meta cycloadduct 3 was found. We propose that at longer reaction times, 5 rearranges to the thermodynamic product 3 via TSD-m passing by a six-membered ring structure and a seven-membered ring structure. The topological analysis of the charge density along the selected reaction coordinates provided some understanding on the intriguing competitive reactions.
机译：密度函数理论和分子方法中原子的量子理论研究了两种竞争方法：二氯丙炔炔氧烷（1）和2-叔丁基丁二烯（1）和2-叔丁基丁二烯之间的二极管 - 桤木反应（DA）和1,4-炔基硼酸盐（AB）（ 2）在二氯甲烷中。我们分析了与定向（Meta和Para）的这种反应相关的几种反应途径。两个竞争反应的逐步机制占据了导致中间两性离子结构的第一步。第二步更有利于通过TSC-M发生的反应，其导致Meta enyne产品5，其是动力学产品。由于相关转变结构（TSB-M）的较高激活能量，不能通过直接环加成来解释元DA产品的形成。找到使用[4 + 3]字符（TSD-M）的替代转换结构，该结构与元环形化图3连接。我们提出在更长的反应时间，5通过通过六元环结构和七元环结构的TSD-M重新排列到热力学产品3。沿着所选反应坐标的电荷密度的拓扑分析为有趣的竞争反应提供了一些了解。

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  • 来源
    《RSC Advances》 |2015年第86期|共9页
  • 作者

    Vallejos Margarita M.; Pellegrinet Silvina C.;

  • 作者单位

    Univ Nacl Nordeste Fac Ciencias Exactas &

    Nat &

    Agrimensura Dept Quim Area Quim Organ RA-3400 Corrientes Argentina;

    Univ Nacl Rosario Fac Ciencias Bioquim &

    Farmaceut Inst Quim Rosario CONICET RA-2000 Rosario Argentina;

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  • 正文语种 eng
  • 中图分类 化学;
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