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首页> 外文期刊>Chemistry: A European journal >Computational study of the mechanism and selectivity of palladium-catalyzed propargylic substitution with phosphorus nucleophiles
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Computational study of the mechanism and selectivity of palladium-catalyzed propargylic substitution with phosphorus nucleophiles

机译：磷亲核试剂催化钯催化炔丙基取代的机理和选择性的计算研究

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摘要

The mechanism and sources of selectivity in the palladium-catalyzed propargylic substitution reaction that involves phosphorus nucleophiles, and which yields predominantly allenylphosphonates and related compounds, have been studied computationally by means of density functional theory. Full free-energy profiles are computed for both H-phosphonate and H-phosphonothioate substrates. The calculations show that the special behavior of H-phosphonates among other heteroatom nucleophiles is indeed reflected in higher energy barriers for the attack on the central carbon atom of the allenyl/propargyl ligand relative to the ligand-exchange pathway, which leads to the experimentally observed products. It is argued that, to explain the preference of allenyl- versus propargyl-phosphonate/phosphonothioate formation in reactions that involve H-phosphonates and H-phosphonothioates, analysis of the complete free-energy surfaces is necessary, because the product ratio is determined by different transition states in the respective branches of the catalytic cycle. In addition, these transition states change in going from a H-phosphonate to a H-phosphonothioate nucleophile.
机译：已通过密度泛函理论对钯催化的炔丙基取代反应中涉及磷亲核试剂并主要产生烯基膦酸酯和相关化合物的选择性机理和来源进行了研究。对H-膦酸酯和H-膦酰硫代酸酯底物都计算了完全自由能分布。计算表明，相对于配体交换途径，H-膦酸酯在其他杂原子亲核试剂中的特殊行为确实反映在对烯丙基/炔丙基配体的中心碳原子的攻击具有更高的能垒上，这导致了实验观察产品。有人认为，要解释在涉及H-膦酸酯和H-膦酰硫代酸酯的反应中，优先选择烯丙基-炔丙基膦酸酯/硫代磷酸酯，必须对整个自由能表面进行分析，因为产物比率是由不同的方法确定的。催化循环各个分支中的过渡态。另外，这些过渡态从H-膦酸酯变为H-硫代膦酸酯亲核体而改变。

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