In a 50 mL three-necked round-bottomed flask, 6.85 g (52.6 mmol) of tetrahydropyran-4-carboxylic acid, 9.79 g (82.3 mmol) of thionyl chloride, and 10 mL of toluene were sequentially added, and a stirrer, thermometer, and reflux condenser were assembled. The reaction system was placed in an oil bath at 80 °C and the reaction was continuously stirred for 1.5 hours. At the end of the reaction, the solvent and excess thionyl chloride were removed by distillation under reduced pressure to afford 7.81 g (100% yield) of tetrahydropyran-4-carbonyl chloride as a light brown liquid. The product was characterized as follows: 1H-NMR (CDCl3, δ/ppm): 1.79-1.93 (2H, m), 1.99-2.06 (2H, m), 2.91-3.00 (1H, m), 3.40-3.49 (2H, m), 3.97-4.03 (2H, m); CI-MS (m/z): 131 [M+1]+.
