We herein report a protocol for the asymmetric 1,4-addition of hydantoins to various Michael acceptors by utilizing Cinchona alkaloid-based chiral quaternary ammonium salt catalysts. Various products were obtained with moderate to good enantioselectivities and accompanying computational investigations helped to identify key interactions responsible for the observed selectivity. DFT calculations along with non-covalent interaction plots reveal the presence of numerous stabilizing non-classical hydrogen bonding interactions along with other non-covalent interactions between the chiral quaternary ammonium salt and hydantoin molecule in the C−C bond forming transition states leading to the formation of the products. In addition, a first proof-of-concept for an analogous a-sulfanylation reaction, albeit with poor selectivity, is reported as well.

中文翻译：

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手性季铵盐催化乙内酰脲的对映选择性加成反应

我们在此报告了利用基于金鸡纳生物碱的手性季铵盐催化剂将乙内酰脲不对称1,4-加成到各种迈克尔受体上的方案。获得了具有中等至良好对映选择性的各种产物，并且伴随的计算研究有助于确定导致观察到的选择性的关键相互作用。DFT 计算以及非共价相互作用图揭示了手性季铵盐和乙内酰脲分子之间在形成过渡态的 C−C 键中存在大量稳定的非经典氢键相互作用以及其他非共价相互作用，从而导致形成的产品。此外，还报道了类似的α-硫酰化反应的第一个概念验证，尽管选择性较差。