Oxygenation of Alkane C−H Bonds with Methyl(trifluoromethyl)dioxirane: Effect of the Substituents and the Solvent on the Reaction Rate

The mechanism of the oxygenation of alkane C−H bonds with methyl(trifluoromethyl)dioxirane
(1a) is studied through the effect of the substituent and solvent on the rate of oxygenation of
2-substituted adamantanes (2). The results suggest a remarkable electron deficiency at the reacting
carbon atom in the transition state leading to the regular oxygenation products. The linearity of
the Hammett plot reveals that the reaction mechanism does not change within a range of
0.15−0.67 units of σI. A change in the solvent does not affect the distribution of the products,
indicating a through-bond transmission of the substituent effect as the origin of the deactivation
of the substrate.

本研究通过考察取代基与溶剂对2-取代金刚烷(2)氧化反应速率的影响，探究了甲基(三氟甲基)二氧杂环丙烷(1a)与烷烃C-H键的氧化反应机制。研究结果表明，在生成常规氧化产物的过渡态中，反应碳原子呈现显著的缺电子特性。哈米特图(Hammett plot)的线性特征显示，在σ_I取值为0.15~0.67的范围内，该反应的机制未发生改变。溶剂的改变并未影响产物分布，这表明取代基效应的键间传递正是底物失活的根源。