Synthesis of 4,6-dichloro-5-iodopyrimidine (8a): a tetrahydrofuran (THF, 2 mL) solution of 4,6-dichloropyrimidine (149 mg, 1.0 mmol) was added to a solution of TMPZnCl-LiCl (1.3 M in THF, 0.85 mL, 1.1 mmol) at 25 °C. The reaction mixture was stirred at this temperature for 45 min. Subsequently, iodine (I2, 381 mg, 1.5 mmol) was dissolved in anhydrous THF (2 mL) and slowly added dropwise to the reaction system and stirring was continued for 0.5 hr. Upon completion of the reaction, the reaction was quenched with saturated aqueous NaHCO3 and aqueous Na2S2O3 (10 mL) and extracted with ether (3 x 50 mL). The organic phases were combined, dried with anhydrous Na2SO4, filtered and the solvent was concentrated in vacuum. Purification by fast column chromatography (CH2Cl2/n-pentane, 1:4) gave the colorless solid product 8a (227 mg, 83% yield). Melting point: 134.9-136.5 °C. 1H NMR (300 MHz, CDCl3) δ: 8.65 (s, 1H). 13C NMR (75 MHz, CDCl3) δ: 166.6, 156.8, 98.9. m/z (relative abundance) by mass spectrum (70 eV, EI): 274 (100) [M+], 239 (27), 97 (12), 83 (12), 57 (21). Infrared spectra (ATR) ν (cm-1): 2923, 2855, 1900, 1499, 1386, 1341, 1296, 1214, 1080, 1014, 790, 763, 745. high-resolution mass spectrometry (EI) calculated value of C4HCl2IN2 (273.8561): measured value 273.8565.
