Gross Christoph, Eitzinger Andreas, Mayer Peter, Ofial Armin R
Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.
Institute of Organic Chemistry, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria.
Chemistry. 2025 Jul 17;31(40):e202501224. doi: 10.1002/chem.202501224. Epub 2025 Jun 25.
The electrophilic reactivities of para-quinone methides (pQMs) with functional groups (FG) at the exocyclic polarized carbon-carbon double bond were determined by photometrically monitoring the kinetics of their reactions with carbanions in dimethyl sulfoxide (DMSO) at 20 °C. The experimental second-order rate constants k were evaluated by the Mayr-Patz equation, that is, the linear free energy relationship lg k = s(N + E), which was leveraged to determine the electrophilicity descriptors E of the pQMs. These electrophilicity parameters E were subsequently used to successfully predict the scope of the pQM reactions with C-, H-, N-, O-, and S-centered nucleophiles. Moreover, the electrophilicity parameters E correlate linearly with a linear combination of quantum-chemically calculated methyl anion affinities (MAAs) and buried volumes (%V). While MAA values mainly reflect the thermodynamic driving force of the carbon-carbon bond formation, %V values take account of the variable steric effects of substituents at the electrophilic δ-position of the pQMs. Knowledge of MAA and %V thus enables chemists to tailor novel pQMs with predictable reactivity properties.
通过在20°C下于二甲基亚砜（DMSO）中用光度法监测对醌甲基化物（pQMs）与碳负离子反应的动力学，测定了其在环外极化碳 - 碳双键处与官能团（FG）的亲电反应活性。实验二级速率常数k通过Mayr - Patz方程进行评估，即线性自由能关系lg k = s(N + E)，利用该方程确定pQMs的亲电描述符E。这些亲电参数E随后被成功用于预测pQMs与以C、H、N、O和S为中心的亲核试剂反应的范围。此外，亲电参数E与量子化学计算的甲基阴离子亲和力（MAA）和埋藏体积（%V）的线性组合呈线性相关。虽然MAA值主要反映碳 - 碳键形成的热力学驱动力，但%V值考虑了pQMs亲电δ位取代基的可变空间效应。因此，了解MAA和%V使化学家能够定制具有可预测反应活性的新型pQMs。
