Ruthenium-catalyzed [2+2] cycloaddition reactions of a 2-oxa-3-azabicyclo[2.2.1]hept-5-ene with unsymmetrical alkynes were investigated. Yields of up to 90% were obtained though regioselectivity was modest. Select cycloadducts could be separated and used to access a highly functionalized [3.2.0] bicyclic structure through reductive cleavage of the N–O bond. These ring-opened products displayed a chemical exchange phenomenon in 1D carbon NMR and required characterization by 2D NMR techniques.
钌催化的2-氧-3-氮杂双环[2.2.1]庚-5-烯与非对称炔烃的[2+2]环加成反应进行了研究。尽管区域选择性较低,但产率高达90%。可分离选择性环加成产物,并通过还原性断裂N-O键来获得高度官能化的[3.2.0]双环结构。这些环开放产物在1D碳核磁共振中显示了化学交换现象,并需要通过2D核磁共振技术进行表征。