Stereoselective Synthesis of Oxabicyclo[2.2.1]heptenes via a Tandem Dirhodium(II)-Catalyzed Triazole Denitrogenation and [3 + 2] Cycloaddition

A novel synthetic strategy for the diastereoselective synthesis of structurally diverse oxabicyclo[2.2.1]­heptenes has been developed, featuring a tandem reaction combining a Rh-catalyzed triazole denitrogenation and a novel type of [3 + 2] cycloaddition reaction. This tandem reaction was thought to proceed via a five-membered oxonium ylide intermediate, which was formed by the intramolecular nucleophilic attack of the carbonyl group on the α-imino metallocarbene followed by an inter- or intramolecular [3 + 2] dipolar cycloaddition with a range of alkynes and alkenes.

本研究开发了一种用于非对映选择性合成结构多样的氧杂双环[2.2.1]庚烯（oxabicyclo[2.2.1]heptenes）的新型合成策略，该策略采用串联反应，将铑（Rh）催化的三唑脱氮反应与新型[3+2]环加成反应相结合。该串联反应推测经由五元环氧鎓叶立德（oxonium ylide）中间体进行：羰基基团对α-亚胺金属卡宾（α-imino metallocarbene）发生分子内亲核进攻以生成该中间体，随后该中间体可与多种炔烃、烯烃发生分子间或分子内的[3+2]偶极环加成反应。