Isoxazolidines represent a very important class of N/O-containing heterocycles used as the key intermediates in the synthesis of more complex cyclic and acyclic compounds, including various biologically active molecules. Here, we present a fast and highly stereoselective approach towards both C-3/4-cis and C-3/4-trans isomers of 3-substituted isoxazolidin-4-ols. The strategy relies on a highly regio- and trans-stereoselective hydroboration–oxidation reaction of the 4,5-unsubstituted 2,3-dihydroisoxazoles with basic hydrogen peroxide. The consecutive oxidation/reduction route, sequentially employing Dess–Martin periodinane and ʟ-selectride, is used for the inversion of the C-3/4-trans relative configuration of the isoxazolidine ring. The significance of the method lies in its variability and applicability to a concise synthesis of various 4-hydroxyisoxazolidines, starting from the readily available C-alkyl/aryl-nitrones. The resemblance to 3-hydroxypyrrolidines certainly makes the 4-hydroxyisoxazolidines important and valuable structural fragments in drug discovery.

中文翻译：

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使用4,5-未取代的2,3-二氢异恶唑的硼氢化-氧化反应合成3-取代的异恶唑烷-4-醇。

异恶唑烷代表了非常重要的一类含N / O的杂环，它们被用作合成更复杂的环状和非环状化合物（包括各种生物活性分子）的关键中间体。在这里，我们提出了一种针对3取代的异恶唑烷-4-醇的C-3 / 4-顺式和C-3 / 4-反式异构体的快速且高度立体选择性的方法。该策略依赖于4,5-未取代的2,3-二氢异恶唑与碱性过氧化氢的高度区域和反式立体选择性硼氢化反应。连续的氧化/还原途径，依次采用Dess-Martin高碘烷和ʟ-selectride进行C-3 / 4-反式的转化异恶唑烷环的相对构型。该方法的重要性在于其从易得的C-烷基/芳基-硝基化合物开始的变异性和适用性，以简化各种4-羟基异恶唑烷的合成。与3-羟基吡咯烷的相似性无疑使4-羟基异恶唑烷在药物发现中成为重要且有价值的结构片段。