Copper-catalysed synthesis of trifluoromethyl allenes via fluoro-carboalkynylation of alkenes

Allenes and trifluoromethyl motifs are considered as important building blocks in materials and pharmaceuticals. A copper-catalysed synthesis of trifluoromethyl allenes utilizing readily available feedstocks under mild and environmentally friendly conditions was developed, which provided an operationally simple and practical platform for the preparation of substituted allenes with a broad substrate scope. Mechanistic explorations showed that a radical-mediated fluorocarboalkynylation and base-promoted step-wise isomerisation of β-CF₃ alkynes were responsible for the formation of the desired allenes.