1053228-28-6

2,4-Dichloro-7H-pyrrolo[2,3-d]pyrimidine (2.0 g, 10.64 mmol) was used as a starting material, which was dissolved in dichloromethane/tetrahydrofuran (DCM/THF, 15 mL/6 mL) mixed solvent. Subsequently, N-chlorosuccinimide (NCS, 1.70 g, 12.76 mmol) was added to the solution. The reaction mixture was placed in a microwave reactor, heated to 90 °C and kept at this temperature for 2.5 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The crude product was purified by fast column chromatography with the eluent being a 9:1 (v/v) hexane/ethyl acetate solvent mixture to afford 2,4,5-trichloro-7H-pyrrolo[2,3-d]pyrimidine (2.2 g, 93% yield) as a white crystalline solid. Mass spectrometry (MS) analysis showed m/z 223.48 [M + 1].

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