Cabré Albert, Rafael Sergi, Sciortino Giuseppe, Ujaque Gregori, Verdaguer Xavier, Lledós Agustí, Riera Antoni
Institute of Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028, Barcelona, Spain.
Departament de Química Inorgànica i Orgànica, Secció Orgànica, Universitat de Barcelona, Martí i Franquès 1, 08028, Barcelona, Spain.
Angew Chem Int Ed Engl. 2020 May 4;59(19):7521-7527. doi: 10.1002/anie.201915772. Epub 2020 Mar 12.
The selective isomerization of strained heterocyclic compounds is an important tool in organic synthesis. An unprecedented regioselective isomerization of 2,2-disubstituted oxetanes into homoallylic alcohols is described. The use of tris(pentafluorophenyl)borane (B(C F ) ) a commercially available Lewis acid was key to obtaining good yields and selectivities since other Lewis acids afforded mixtures of isomers and substantial polymerization. The reaction took place under exceptionally mild reaction conditions and very low catalyst loading (0.5 mol %). DFT calculations disclose the mechanistic features of the isomerization and account for the high selectivity displayed by the B(C F ) catalyst. The synthetic applicability of the new reaction is demonstrated by the preparation of γ-chiral alcohols using iridium-catalyzed asymmetric hydrogenation.
张力杂环化合物的选择性异构化是有机合成中的一种重要工具。本文描述了一种前所未有的2,2-二取代氧杂环丁烷区域选择性异构化为高烯丙醇的反应。使用三（五氟苯基）硼烷（B(C₆F₅)₃）这种市售的路易斯酸是获得良好产率和选择性的关键，因为其他路易斯酸会产生异构体混合物并伴有大量聚合反应。该反应在异常温和的反应条件下进行，催化剂负载量极低（0.5 mol%）。密度泛函理论（DFT）计算揭示了异构化的机理特征，并解释了B(C₆F₅)₃催化剂所表现出的高选择性。通过使用铱催化的不对称氢化反应制备γ-手性醇，证明了该新反应的合成适用性。
