Department of Chemistry, University of Pavia, Viale Taramelli, 12, Pavia 27100, Italy.
Department of Chemistry, College of Science, Salahaddin University-Erbil, Erbil 44002, Iraq.
J Org Chem. 2021 Jun 4;86(11):7672-7686. doi: 10.1021/acs.joc.1c00706. Epub 2021 May 25.
A novel approach for the formation of anomeric carbon-functionalized furanoside systems was accomplished through the employment of an oxo-rhenium catalyst. The transformation boasts a broad range of nucleophiles including allylsilanes, enol ethers, and aromatics in addition to sulfur, nitrogen, and hydride donors, able to react with an oxocarbenium ion intermediate derived from furanosidic structures. The excellent stereoselectivities observed followed the Woerpel model, ultimately providing 1,3--1,4- systems. In the case of electron-rich aromatic nucleophiles, an equilibration occurs at the anomeric center with the selective formation of 1,3--1,4- systems. This anomalous result was rationalized through density functional theory calculations. Different oxocarbenium ions such as those derived from dihydroisobenzofuran, pyrrolidine, and oxazolidine heterocycles can also be used as a substrate for the oxo-Re-mediated allylation reaction.
通过使用氧化锇催化剂，成功地开发了一种新型的形成糖苷碳原子功能化呋喃糖系统的方法。该转化具有广泛的亲核试剂，包括烯丙基硅烷、烯醇醚和芳香族化合物，以及硫、氮和氢供体，能够与衍生自呋喃糖结构的氧碳正离子中间体反应。观察到的优异立体选择性遵循 Woerpel 模型，最终提供了 1,3-1,4-系统。在富电子芳香族亲核试剂的情况下，在糖苷中心发生平衡，选择性地形成 1,3-1,4-系统。这一反常结果通过密度泛函理论计算得到了合理化。不同的氧碳正离子，如二氢异苯并呋喃、吡咯烷和恶唑烷杂环衍生的氧碳正离子，也可以用作氧化锇介导的烯丙基化反应的底物。
