(1,1,2,2-Tetrafluorobut-3-en-1-yl)zinc bromide was prepared by insertion of the zinc–silver couple into the CF2–Br bond of commercially available 4-bromo-3,3,4,4-tetrafluorobut-1-ene in DMF at 0 °C for 0.5 h, The resultant polyfluorinated zinc reagent was found to be thermally stable at ambient temperature and storable for at least 1.5 years in the refrigerator. This CF2CF2-containing organozinc reagent could be easily transmetallated to copper species, which underwent cross-coupling reactions with various aromatic iodides or acyl chlorides to produce a broad range of CF2CF2-containing organic molecules in good-to-excellent yields. Therefore, the zinc reagent could become a new and practical synthetic tool for producing functional molecules with a CF2CF2 fragment.

Guided by theoretical calculations, we predicted that 5,5,6,6-tetrafluoro-1-methoxycyclohex-1-ene, a new structural motif, exhibits a large negative dielectric anisotropy, and then developed a synthetic strategy for the preparation of the novel tetrafluorinated tricyclic mesogen in twelve reaction steps starting from a commercially available fluorinated starting material. During the evaluation of its liquid-crystalline characteristics, the tetrafluorinated mesogen was found to display low birefringence and a large negative dielectric anisotropy, confirming that its molecular structure is a reasonable design for the further development of novel mesogenic molecules with large negative dielectric anisotropies.

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