C(N(CC)C(C)C)(C)C.[Br-].[Li+].[F:12][C:13]([F:29])([F:28])[C:14]1[CH:15]=[C:16]([C:20]2([CH:26]=O)[CH2:25][CH2:24][O:23][CH2:22][CH2:21]2)[CH:17]=[CH:18][CH:19]=1.[CH3:30][CH2:31][O:32][C:33]([CH3:35])=[O:34]>C1COCC1.Cl>[F:12][C:13]([F:29])([F:28])[C:14]1[CH:15]=[C:16]([C:20]2([CH:26]=[CH:35][C:33]([O:32][CH2:31][CH3:30])=[O:34])[CH2:25][CH2:24][O:23][CH2:22][CH2:21]2)[CH:17]=[CH:18][CH:19]=1
N,N-diisopropylethylamine (2.95 mL, 16.9 mmol) and anhydrous lithium bromide (489 mg, 5.63 mmol) were added to a stirred solution of 4-(3-(trifluoromethyl)phenyl)-tetrahydro-2H-pyran-4-carbaldehyde (485 mg, 1.88 mmol) in THF (15 mL). After 20 min., triethyl phosphonoacetate (1.12 mL, 5.63 mmol) was added and the mixture was stirred at room temperature for 16 h. Additional N,N-diisopropylethylamine (980 μL, 5.64 mmol) was added and stirring was continued for additional 160 min. The reaction mixture was diluted with EtOAc and 1N aq. HCl solution. The organic layer was separated, washed with 1N aq. HCl solution, brine, dried (Na2SO4), filtered, and concentrated under vacuum to obtain a thin yellow oil which was chromatographed on silica gel (Teledyne-Isco RediSep 12 g column). Elution with 5%, 10%, and 20% EtOAc in hexanes afforded ethyl 3-(4-(3-(trifluoromethyl)phenyl)tetrahydro-2H-pyran-4-yl)acrylate (569 mg, 92% yield) as a viscous yellow oil. 1H NMR (400 MHz, CDCl3): δ ppm 7.38-7.68 (m, 4H), 6.98 (d, 1H), 5.71 (d, 1H), 4.19 (q, 2H), 3.76 (dd, 4H), 2.06-2.34 (m, 4H), 1.29 (t, 3H).
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