90-60-8

100-97-0

120-83-2

90-60-8

The general procedure for the synthesis of 3,5-dichlorosalicylaldehyde from urotropine and 2,4-dichlorophenol was as follows: first, 2,4-dichlorophenol (10.0 g, 61.3 mmol) and hexamethylenetetetramine (17.2 g, 122.6 mmol) were dissolved in 80 mL of methanesulfonic acid, and the reaction mixture was heated and stirred for 1.5 hours at 100 °C. After the reaction was completed, the reaction mixture was diluted with ethyl acetate, and the organic layer was washed sequentially with water and saturated sodium bicarbonate solution, and then dried with anhydrous magnesium sulfate. The solvent was removed by evaporation under reduced pressure to give the crude product. The crude product was purified by column chromatography using ethyl acetate/hexane gradient elution to afford the target compound 3,5-dichloro-2-hydroxybenzaldehyde (INT-01) as a yellow oil (7.5 g, 64% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ11.39 (s, 1H), 7.64 (s, 1H), 7.52 (s, 1H). Liquid chromatography (LC) analytical conditions: C-18 column, 5 min to 95% acetonitrile/water gradient elution, flow rate 1.7 mL/min, detection wavelength 254 nm, column temperature 23 ℃, retention time (tr) = 3.95 min.