[CH3:1][Si](C)(C)N[Si](C)(C)C.[K].[O:11]1[CH2:16][CH2:15][CH:14]([CH2:17][CH:18]=O)[CH2:13][CH2:12]1.[Cl-].[NH4+]>[Br-].C[P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.O1CCCC1>[CH2:17]([CH:14]1[CH2:15][CH2:16][O:11][CH2:12][CH2:13]1)[CH:18]=[CH2:1]
Methyltriphenylphosphonium bromide (2.18 g, 6.10 mmol) was suspended in tetrahydrofuran (50 mL) under an argon atmosphere, and potassium hexamethyldisilazane (toluene solution, 0.5 mol/L) (11.0 mL, 5.49 mmol) was added dropwise thereto at room temperature, followed by stirring for 1 hr. The reaction mixture was cooled to −78° C., a solution of (tetrahydropyran-4-yl)acetaldehyde (391 mg, 3.05 mmol) in tetrahydrofuran (10 mL) was added dropwise thereto, and the mixture was warmed to room temperature, followed by stirring for 1 hr. Saturated aqueous ammonium chloride solution was added to the reaction mixture and the mixture was extracted with diethyl ether. The organic layer was washed with brine and dried over anhydrous magnesium sulfate. The desiccant was filtered off, followed by concentration under reduced pressure. The residue was purified by silica gel column chromatography (hexane only→hexane:ethyl acetate=9:1) to afford 4-(prop-2-en-1-yl)tetrahydro-2 H-pyran as a pale yellow oil (245 mg).
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