An efficient and diversity-oriented access to functionalized pyrrolidin-2-ones through an Ugi reaction of readily available starting materials with a subsequent transformation is described. A two-step reaction sequence of a four-component Ugi reaction and an intramolecular radical-cyclization reaction leads to the chemo- and regioselective formation of a single product with high atom economy and good to high yields. The radicalization of the pseudopeptides generated from the first step by a cavitational mechanism produces the key intermediate for the ultrasound-activated formation of γ-lactams as the final products by β-Michael addition. Among the advantages of this approach are its use of cavitation bubble implosion as an exclusive path to radicalization of the polyfunctional Ugi adduct, its high selectivity, and its short reaction times.

中文翻译：

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通过四组分 Ugi/5-endo-trig 分子内自由基环化反应合成高度取代的 Pyrrolidin-2-ones 的超声活化原子经济方法

描述了通过易于获得的起始材料的 Ugi 反应和随后的转化，获得功能化的 pyrrolidin-2-ones 的高效和面向多样性的途径。四组分 Ugi 反应和分子内自由基环化反应的两步反应序列导致具有高原子经济性和高产率的单一产物的化学和区域选择性形成。通过空化机制对第一步产生的假肽进行自由基化，产生了关键中间体，用于超声激活形成 γ-内酰胺作为 β-迈克尔加成的最终产物。这种方法的优点包括使用空化气泡内爆作为多官能 Ugi 加合物自由基化的唯一途径、高选择性和短反应时间。