| 摘要 |
PROBLEM TO BE SOLVED: To obtain a new ethynylnaphthalene derivative having an ultrahigh anisotropy of refractive index, a high upper limit temperature of nematic phase and a low viscosity, excellent in compatibility, liquid crystal properties and high-speed responsiveness and useful as a liquid crystal element, etc. SOLUTION: This compound is represented by formula I [R is a 1-10C alkyl; A-ring is trans-1,4-cyclohexylene or a (n) (F-substituted)1,4-phenylene; L is CH2CH2 or a single bond; Xa, Xb and Xc are each H or F], e.g. 2-(3,4- difluorophenyl)ethynyl-6-(trans-4-propyl)cyclohexylnaphthalene. The compound represented by formula I is obtained by reacting a triflate represented by formula II (Tf is trifluoromethanesulfonuyl) with an ethynylbenzene derivative represented by formula III in the presence of a transition metal catalyst such as a palladium-based catalyst in a solvent such as dimethylformamide.
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