[2+2] Photocycloaddition of Symmetrically Disubstituted Alkenes to 2(5H)-Furanones: Diastereoselective Entry to 1,2,3,4-Tetrasubstituted Cyclobutanes
作者:Sònia Parés、Pedro de March、Josep Font、Ramon Alibés、Marta Figueredo
DOI:10.1002/ejoc.201100067
日期:2011.7
A study on the [2+2] photochemical cycloaddition of 1,4-difunctionalized 2-butenes to 2(5H)-furanones is presented. These reactions deliver 1,2,3,4-tetrasubstituted cyclobutanes with suitable functionalization in the four side chains for further synthetic elaboration. The effects of the substituents in both the lactone and the 2-butene on the stereoselectivity of the photochemical reaction have been
介绍了 1,4-双官能化 2-丁烯到 2(5H)-呋喃酮的 [2+2] 光化学环加成的研究。这些反应提供了 1,2,3,4-四取代的环丁烷,在四个侧链中具有合适的官能化,用于进一步的合成加工。已经评估了内酯和 2-丁烯中的取代基对光化学反应立体选择性的影响。从 (Z)-2-丁烯开始,在光敏条件下,烯烃的竞争性顺/反异构化会抑制环加成过程。发现限制在中等大小环内的顺式双键的存在不会阻止中间体 1,4-双自由基中的键旋转。