Stereospecific Consecutive Epoxide Ring Expansion with Dimethylsulfoxonium Methylide
作者:Ekaterina D. Butova、Anastasiya V. Barabash、Anna A. Petrova、Christian M. Kleiner、Peter R. Schreiner、Andrey A. Fokin
DOI:10.1021/jo101330p
日期:2010.9.17
Consecutive ring-expansion reactions of oxiranes with dimethylsulfxonium methylide were studied experimentally and modeled computationally at the density functional theory (DFT) and second-order Møller−Plesset (MP2) levels of theory utilizing a polarizable continuum model (PCM) to account for solvent effects. While the epoxide to oxetane ring expansion requires 13−17 kcal mol−1 activation and occurs
在密度泛函理论(DFT)和二阶Møller-Plesset(MP2)理论水平下,利用极化可连续性模型(PCM)来考虑溶剂效应,从而研究了肟酮与二甲基亚砜基甲基的连续扩环反应并对其进行了建模。 。虽然环氧乙烷到环氧乙烷的环膨胀需要13-17 kcal mol -1的活化并在升高的温度下发生,但环膨胀到氧杂环戊烷的阻隔性更高(约25 kcal mol -1),并且需要加热到125°C。这些氧杂环戊烷向六元恶烷的进一步扩展受到高势垒(约40 kcal mol -1)的阻碍)。我们观察到对映体纯度的完全保守性,即对映体2-单-和2,2-二取代的环氧化物和氧杂环丁烷与二甲基亚砜基甲基化的亲核环扩展。这是从环氧乙烷高产率制备光学活性的四元和五元环状醚的简便通用方法。