Modular Synthesis of Multifunctionalized CF3-Allenes through Selective Activation of Saturated Hydrocarbons

Catalytic 1,4-dicarbofunctionalization of 1,3-enynes is a powerful strategy for the synthesis of polysubstituted allenes. Despite impressive progress, such a strategy is still restricted to the use of alkyl-metallic reagents or pre-activated radical precursors, thus limiting its functional group compatibility and atom economy. Herein, we report that through the combination of decatungstate photo-hydrogen atom transfer and nickel catalysis, a three-component 1,4-dicarbofunctionalization of 2-trifluoromethyl-1,3-enynes is achieved. This strategy allows the modular synthesis of tetrasubstituted CF3-allenes under exceptionally mild conditions. A variety of electrophiles such as aryl bromides, alkenyl bromides, acyl chlorides, and alkynyl bromides were successfully employed as traps to lead to the desired products. Another significant advantage is that the most abundant hydrocarbons are used as feedstocks, and a wide range of synthetically versatile functional groups and complex drug-like structures can be easily incorporated. Based on experimental and density functional theories, a possible catalytic cycle involving 1,3-nickel rearrangement is proposed.