Phosphorus trichloride (125 g, 815 mmol) was slowly added dropwise to N,N-dimethylformamide (74.5 g, 1019 mmol) in a flame-dried round-bottomed flask at 0 °C while stirring was maintained. After the dropwise addition was completed, the reaction mixture was slowly warmed to room temperature and maintained for 30 min, followed by cooling again to 0 °C. At this temperature, cyclohexanone (50 g, 509 mmol) was slowly added dropwise. The reaction mixture was warmed to room temperature and stirred for 12 hours. After completion of the reaction, the reaction mixture was poured into ice water and quenched with sodium bicarbonate solution. After neutralization, extraction was carried out with ethyl acetate (100 mL x 3) and the organic phase was washed with water and brine sequentially. The organic phases were combined, dried over anhydrous sodium sulfate and filtered, and concentrated under reduced pressure to afford the target product 2-chlorocyclohexyl-1-allylaldehyde (160 g, 87% yield).1H NMR (CDCl3, 400MHz) δ: 1.74-1.75 (m, 2H), 1.76-1.78 (m, 2H), 2.24-2.27 (m, 2H), 2.53- 2.59 (m, 2H), 7.25 (s, 1H).
