A two‐stage protocol was developed for accessing nitrocyclopropanes that bear a thioester group and three stereogenic centers. This protocol achieves practical overall yields ranging from 54% to 75%, along with high levels of stereoselectivity (single diastereomer with up to 98% ee). Brominated monothiomalonate (Br‐MTM) is used as an α‐bromo thioacetate equivalent, which reacts efficiently with nitroolefins in the presence of a low catalyst loading (0.5 mol%) of cinchona alkaloid squaramide under both "on water" and organic homogeneous conditions. The obtained α‐bromo‐γ‐nitrothioesters undergo an anti‐selective decarboxylation and intramolecular SN2 cyclization process, leading to the formation of desired cyclopropanes. Control experiments were conducted alongside computational studies in order to gain insights into the observed stereoselectivities.

中文翻译：

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有机催化对映选择性合成带有硫酯基团和三个立构中心的硝基环丙烷

开发了一个两阶段方案来获取带有硫酯基团和三个立体中心的硝基环丙烷。该方案实现了 54% 至 75% 的实际总产率，以及高水平的立体选择性（单一非对映异构体的 ee 高达 98%）。溴化单硫代丙二酸酯 (Br-MTM) 用作 α-溴代硫代乙酸酯等价物，在“水上”和有机均相条件下，在低催化剂负载量 (0.5 mol%) 金鸡纳生物碱方酰胺存在下，可与硝基烯烃高效反应。所得的α-溴-γ-硝基硫酯经历反选择性脱羧和分子内SN2环化过程，从而形成所需的环丙烷。对照实验与计算研究一起进行，以便深入了解观察到的立体选择性。