[O:1]1[CH2:6][CH2:5][C:4](=[O:7])[CH2:3][CH2:2]1.CN(C)P(N(C)C)(N(C)C)=O.[CH:19]([N-]C(C)C)(C)[CH3:20].[Li+].ICC>O1CCCC1.C(OCC)(=O)C>[CH2:19]([CH:3]1[C:4](=[O:7])[CH2:5][CH2:6][O:1][CH2:2]1)[CH3:20]To a mixture of tetrahydropyran-4 one (5 g, 0.05 mol) and hexamethylphosphoramide (9 mL) in tetrahydrofuran (100 mL) was added lithium diisopropylamide (34.7 mL, 0.062 mol) dropwise at −78° C. under N2. After the addition the mixture was stirred for 0.5 h at −78° C. Iodoethane (7.78 g, 0.199 mol) was added to the mixture dropwise. The ddresulting mixture was stirred for 12 hours at room temperature. TLC (petroleum ether:ethyl acetate=4:1) indicated the reaction was not complete, the mixture was quenched with aqueous ammonium chloride (100 mL), extracted with ethyl acetate (3×50 mL), the combined organic layers was concentrated in vacuo and the residue was purified by chromatography on silica using petroleum ether: ethyl acetate from 15:1 to 10:1 to yield compound the title compound (2.5 g, 39.1%) as a colorless liquid. 1H NMR (400 MHz, CD3OD) δ (ppm): 4.15 (m, 2H), 3.80 (m, 1H), 3.45 (m, 1H), 2.58 (m, 1H), 2.48 (m, 2H), 1.81 (m, 1H), 1.30 (m, 1H), 0.92 (m, 3H).
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