DFT Studies on Ni-Mediated C-F Cleavage for the Synthesis of Cyclopentadiene Derivatives

Density functional theory calculations have been performed to study the detailed mechanism of Ni-mediated [3+2] cycloaddition of 2-trifluoromethyl-1-alkenes with alkynes via cleavage of two C-F bonds. It was found that the reaction pathway involves oxidative cyclization, the first β-fluorine elimination, and then intramolecular 5-endo insertion of difluoroalkene, followed by the second cleavage of C-F bond, and finally the dissociation of difluorides yields the fluorine-containing product cyclopentadienes in sequence. The overall rate-determining step is the combined processes of the β-fluorine elimination and the 5-endo insertion. Furthermore, we investigated the effect of different ligands and the regioselectivity of asymmetric alkynes. The detailed energy profiles and structures are presented in this study.