An efficient and practical synthetic approach was developed for the tandem synthesis of trisubstituted 2-pyrone derivatives from sulfoxonium ylides and cyclopropenones. This [3?3] annulation reaction was carried out under transition-metal-free conditions. A broad range of functional groups were tolerant under mild conditions, and a variety of 2-pyrones were obtained in moderate to good yields.

中文翻译：

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亚砜与环丙烯酮的无过渡金属[3 + 3]环化反应，用于合成2-吡喃酮

开发了一种有效且实用的合成方法，用于从亚砜基鎓盐和环丙烯酮串联合成三取代的2-吡喃酮衍生物。该[3→3]环化反应在无过渡金属的条件下进行。各种官能团在温和条件下均能耐受，并且以中等至良好的产率获得了各种2-吡喃酮。