4-Chloro-1-H-imidazo[4,5-c]pyridine

91184-02-0

2770-01-6

The general procedure for the synthesis of 4-chloroimidazo[4,5-C]pyridine using the compound (CAS: 91184-02-0) as starting material was as follows: compound 3 (255 mg, 1.88 mmol) was dissolved in 10 mL of phosphorus oxytrichloride (POCl3), and the reaction was stirred for 3 hr at 110 °C until the reaction solution became clear. Upon completion of the reaction, the excess phosphorous trichloride was removed under vacuum. Subsequently, ice water was added to the reaction mixture, the pH was adjusted to about 9 by slowly adding ammonia dropwise, and an equal volume of methanol (MeOH) was added. At this point, a precipitate appeared in the reaction mixture and the precipitate was collected by filtration. The filtrate was adsorbed on silica gel and purified by silica gel column chromatography, the eluent being a mixture of ethyl acetate (EA) and 5% methanol (MeOH), resulting in the target product 4 in 83% yield. The results of high-resolution mass spectrometry (HRMS-ESI) analysis were as follows: m/z calculated value (C6H5ClN3 [M+H]+) was 154.0166, and the measured value was 154.0171.