[H-].[Na+].[F:3][C:4]1[CH:5]=[C:6]([CH2:11][C:12]#[N:13])[CH:7]=[CH:8][C:9]=1[F:10].Br[CH2:15][CH2:16][O:17][CH:18]1[CH2:23][CH2:22][CH2:21][CH2:20][O:19]1>C1COCC1>[F:3][C:4]1[CH:5]=[C:6]([CH:11]([CH2:15][CH2:16][O:17][CH:18]2[CH2:23][CH2:22][CH2:21][CH2:20][O:19]2)[C:12]#[N:13])[CH:7]=[CH:8][C:9]=1[F:10]14.4 g of sodium hydride as a 60% dispersion in oil are suspended in 250 ml of THF and cooled in a water bath. A solution of 50 g of 3,4-difluorophenylacetonitrile in 50 ml of THF is added dropwise, the mixture is then left to stand for 3 hours at RT and a solution of 68.16 g of 2-(2-bromoethoxy)tetrahydropyran in 100 ml of THF is added dropwise. After one night at RT, the mixture is acidified with a buffer of pH 2, the THF is evaporated off and the residue is taken up with water and extracted with ether. The extract is washed twice with a buffer solution of pH 4 and then with water and with saturated sodium chloride solution. It is decanted and the organic phase is dried over MgSO4 and concentrated under vacuum. The residue is chromatographed on silica using pure toluene and then toluene containing up to 3% of AcOEt as the eluent to give 49.5 g of the expected product.
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