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首页> 外文期刊>Chemistry: A European journal >Divergent Pathways and Competitive Mechanisms of Metathesis Reactions between 3-Arylprop-2-ynyl Esters and Aldehydes: An Experimental and Theoretical Study
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Divergent Pathways and Competitive Mechanisms of Metathesis Reactions between 3-Arylprop-2-ynyl Esters and Aldehydes: An Experimental and Theoretical Study

机译：3-芳基丙-2-炔基酯与醛之间复分解反应的不同途径和竞争机理：实验和理论研究

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摘要

Mechanistic studies of the reaction between 3-arylprop-2-ynyl esters and aldehydes catalyzed by BF_3·Et_2O were performed by isotopic labeling experiments and quantum chemical calculations. The reactions are shown to proceed by either a classical alkyne–carbonyl metathesis route or an unprecedented addition–rearrangement cascade. Depending on the structure of the starting materials and the reaction conditions, the products of these reactions can be Morita–Baylis–Hillman (MBH) adducts that are unavailable by traditional MBH reactions or E- and Z-a,b-unsaturated ketones. ~(18)O-Labeling studies suggested the existence of two different reaction pathways to the products. These pathways were further examined by quantum chemical calculations that employed the DFT(wB97XD)/6-311+G(2d,p) method, together with the conductor-like screening model for realistic solvation (COSMO-RS). By using the wB97XD functional, the accuracy of the computed data is estimated to be 1–2 kcal mol~(-1), shown by the careful benchmarking of various DFT functionals against coupled cluster calculations at the CCSD(T)/aug-cc-pVTZ level of theory. Indeed, most of the experimental data were reproduced and explained by theory and it was convincingly shown that the branching point between the two distinct mechanisms is the formation of the first intermediate on the reaction pathway: either the fourmembered oxete or the six-membered zwitterion. The deep mechanistic understanding of these reactions opens new synthetic avenues to chemically and biologically important α,β-unsaturated ketones.
机译：通过同位素标记实验和量子化学计算，研究了BF_3·Et_2O催化3-芳基丙-2-炔基酯与醛的反应机理。反应是通过经典的炔烃-羰基复分解路线或前所未有的加成-重排级联进行的。根据原料的结构和反应条件，这些反应的产物可以是传统的MBH反应无法获得的Morita–Baylis–Hillman（MBH）加合物或E-和Z-a，b-不饱和酮。 〜（18）O-标签研究表明产物存在两种不同的反应途径。通过采用DFT（wB97XD）/ 6-311 + G（2d，p）方法的量子化学计算，以及用于实际溶剂化的类似导体的筛选模型（COSMO-RS），进一步检查了这些途径。通过使用wB97XD函数，计算数据的准确性估计为1-2 kcal mol〜（-1），这是通过在CCSD（T）/ aug-cc上针对耦合簇计算对各种DFT函数进行仔细基准测试而显示的-pVTZ理论水平。实际上，大多数实验数据都是通过理论重现和解释的，令人信服地表明，两种不同机理之间的分支点是反应路径上第一中间体的形成：四元氧杂环丁烷或六元两性离子。对这些反应的深刻机理理解为化学和生物学上重要的α，β-不饱和酮打开了新的合成途径。

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