[CH3:1][O:2][C:3]([C:5]1([OH:8])[CH2:7][CH2:6]1)=[O:4].[O:9]1[CH:14]=[CH:13][CH2:12][CH2:11][CH2:10]1.[NH+]1C=CC=CC=1.C1(C)C=CC(S(O)(=O)=O)=CC=1>C(Cl)Cl.C(OCC)C>[CH3:1][O:2][C:3]([C:5]1([O:8][CH:10]2[CH2:11][CH2:12][CH2:13][CH2:14][O:9]2)[CH2:7][CH2:6]1)=[O:4]
Hydroxy-cyclopropanecarboxylic acid methyl ester (5.07 g, 43.71 mmol) was dissolved in methylene chloride (75 mL) and 3,4-dihydro-2H-pyran (3.86 g, 45.90 mmol) was added followed by pyridinium-p-toluene-sulfonic acid (1.10 g, 4.37 mmol). The reaction stirred at 25° C. for 3 h. The reaction was concentrated in vacuo to give a clear oil. The oil was dissolved in diethyl ether (75 mL), washed with saturated aqueous brine solution (25 mL), dried over sodium sulfate and concentrated in vacuo to an oil. The oil was passed through a plug of silica gel (Merck silica gel 60, 40-63 μm; 100% ethyl acetate) to afford 1-(tetrahydro-pyran-2-yloxy)-cyclopropanecarboxylic acid methyl ester (7.49 g, 86%) as a clear oil: H1-NMR (400 MHz, CDCl3) δ 1.14-1.42 (4H, m), 1.88-3.46 (6H, m), 3.46-3.54 (1H, m), 3.70-3.72 (3H, m), 3.82-3.90 (1H, m), 4.81-4.96 (1H, m).
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