Palani Vignesh, Wendlandt Alison E
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
J Am Chem Soc. 2023 Sep 13;145(36):20053-20061. doi: 10.1021/jacs.3c06935. Epub 2023 Aug 30.
Small, strained ring systems are important pharmacophores in medicinal chemistry and versatile intermediates in organic synthesis. However, the kinetic and thermodynamic instability of many strained organic molecules renders them challenging to prepare. Here, we report a strain-inducing positional alkene isomerization reaction that provides mild and selective access to cyclobutene building blocks from readily obtained cyclobutylidene precursors. This endergonic isomerization relies on the sequential and synergistic action of a decatungstate polyanion photocatalyst and cobaloxime co-catalyst to store potential energy in the form of ring strain. The versatility of the cyclobutene products is demonstrated through diverse subsequent strain-releasing transformations. Mechanistic studies reveal a steric basis for strain-selective product formation.
小的张力环体系是药物化学中的重要药效基团和有机合成中的通用中间体。然而，许多张力有机分子的动力学和热力学不稳定性使得它们的制备具有挑战性。在此，我们报道了一种诱导应变的位置烯烃异构化反应，该反应可从容易获得的亚环丁基前体温和且选择性地获得环丁烯结构单元。这种吸能异构化依赖于十钨酸根聚阴离子光催化剂和钴肟助催化剂的顺序协同作用，以环张力的形式储存势能。通过各种后续的应变释放转化展示了环丁烯产物的多功能性。机理研究揭示了应变选择性产物形成的空间基础。
