A detailed study of the Ni-catalyzed [4+3+2] cycloaddition reaction between ethyl cyclopropylideneacetate and dienynes has been conducted, resulting in the development of a new method for the synthesis of compounds containing nine-membered rings. We studied the reactivity of various dienynes, together with their substituent and conformational effects. The mechanism of the reaction was probed by examining the stoichiometric reactions of the Ni complexes and dienynes.

Treatment of tetrafluoroethene (TFE) with diethylzinc in the presence of lithium iodide gave 1,1,2-trifluoro-1-butene in moderate yield. In the absence of lithium iodide, however, the nucleophilic addition of diethylzinc to TFE proceeded very slowly to afford ethyl 1,1,2,2-tetrafluorobutylzinc. The addition of lithium iodide to a solution of ethyl-1,1,2,2-tetrafluorobutylzinc resulted in a smooth transformation into 1,1,2-trifluoro-1-butene. In the presence of lithium chloride, the reaction of TFE with benzyl or allyl Grignard reagents afforded the corresponding monosubstituted products in good to excellent yields.

Trifluorovinylzinc is a common synthetic intermediate for trifluorovinyl derivatives, including α,β,β-trifluorostyrenes and hexafluorobutadiene. Here, we report a novel synthetic approach for the formation of trifluorovinylzinc chloride via a C–F bond activation of tetrafluoroethylene (TFE), which is an industrially cost-effective bulk feedstock with a negligible GWP. The present system provides a practical synthetic route to various trifluorovinyl derivatives with very low energy consumption.