25392-41-0

4-(Chloromethyl)-7-hydroxy-2H-chromen-2-one is a thiol-reactive, cell-permeant fluorescent probe that easily passes through cell membranes.

638-07-3

108-46-3

25392-41-0

A mixture of resorcinol (1.0 mmol), ethyl 4-chloroacetoacetate (1.5 mmol) and MNESA (0.075 g) was placed in a round-bottomed flask and the reaction was stirred at 90 °C. The progress of the reaction was monitored by thin layer chromatography (TLC) and after confirming the completion of the reaction, the reaction mixture was cooled to room temperature. The catalyst MNESA was separated from the reaction mixture using an external magnetic field. Subsequently, water was added to the reaction mixture and the target product, 4-chloromethyl-7-hydroxychromen-2-one, was extracted with ethyl acetate (EtOAc, 3 × 10 mL). The organic layers were combined, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure to give the crude product. For further purification, the crude product was recrystallized in ethanol to obtain high purity 4-chloromethyl-7-hydroxychromen-2-one.