Catalytic double [2 + 2] cycloaddition relay enabled C-C triple bond cleavage of yne-allenones

Heng Li, Wen-Juan Hao, Mian Wang, Xue Qin, Shu-Jiang Tu,* Peng Zhou, Guigen Li, Jianyi Wang,* and Bo Jiang*

An unusual catalytic double [2 + 2] cycloaddition relay reaction of yne-allenones with unactivated alkenes and alkynes has been achieved, which enabled C-C triple bond cleavage to access more than 60 examples of functionalized phenanthren-9-ols with generally good yields. This reaction provides a regioselective and practical method for the construction of carbocyclic ring systems with a high degree of functional group compatibility. Aside from surveying the scope of this transformation, mechanistic details of this process are provided by conducting systematic theoretical calculations.

Org. Lett. 2018, 20, 4362-4366