Dichloromethane (30 ml) was added to 3-(4′-ethoxy-2,2′,3,3′-tetrafluorobiphenyl-4-yl)-6-(4-propylcyclohexyl)tetrahydropyran-2-ol (12) (2.29 g) prepared in the tenth step. Triethylsilane (1.93 g) and a boron trifluoride-diethyl ether complex (2.37 g) were added dropwise to the solution at −30° C. After 3 hours of stirring, water (30 ml) was added to give two layers. The organic layer was washed with water, dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure. The residue was purified by silica gel chromatography (silica gel: 200 g, eluent: heptane/ethyl acetate=80/20 by volume) and then by recrystallization (heptane/ethyl acetate=90/10 by volume) to give 5-(4′-ethoxy-2,2′,3,3′-tetrafluorobiphenyl-4-yl)-2-(4-propylcyclohexyl)tetrahydropyran (13) (0.8 g) in 36% yield.
