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General procedure for the synthesis of 5,7-dichloroimidazo[1,2-c]pyrimidines from 7-chloroimidazo[1,2-c]pyrimidin-5(6H)-ones: 38.3 g (225.86 mmol) of 7-chloroimidazo[1,2-c]pyrimidin-5(6H)-one was suspended in 450.2 g (2936 mmol) of phosphorochloridic acid chloride under argon protection. The reaction mixture was heated to 120°C for 4 hours. Upon completion of the reaction, the excess phosphoryl chloride was evaporated under reduced pressure and the residue was azeotropically distilled with toluene to further remove the residual phosphoryl chloride. The residue was suspended in water and the pH was adjusted to 7 with saturated aqueous sodium bicarbonate and the precipitated solid was collected by filtration. The solid was washed with water and dried for 18 hours using phosphorus pentoxide as the drying agent. Finally 33.5 g of the target product 5,7-dichloroimidazo[1,2-c]pyrimidine was obtained in 67% yield. The product was analyzed by LCMS (Method 6): retention time Rt = 1.01 min, m/z = 189 (M + H)+. 1H-NMR (400 MHz, DMSO-d6) data were as follows: δ= 8.11 (s, 1H), 7.94 (s, 1H), 7.81 (s, 1H).

[1] Patent: US2010/113441, 2010, A1. Location in patent: Page/Page column 27
[2] ACS Medicinal Chemistry Letters, 2015, vol. 6, # 1, p. 42 - 46
[3] Patent: US2006/84650, 2006, A1. Location in patent: Page/Page column 87