Benzoyl chloride → 1-(5-Bromopyridin-2-yl)thiourea

1.1 Ammoniumthiocyanat (76 mmol, 1.2 eq.) is dissolved in acetone (75 ml) and benzoylchloride (1 eq.) is added dropwise. 20 min after stirring at RT, the reaction is heated to reflux. 2-Amino-5-bromopyridine (71 mmol) in acetone (50 ml) is added and 30 min heated to reflux. Afterwards, the reaction solution is poured onto ice. The precipitate is filtered and washed with water/methanol (1:1). The precipitate is dissolved in 2M NaOH (120 ml) at 80° C. and stirred 10 min at 80° C. The solution is poured into an HCl solution (5%) at 0° C. The pH of the solution is adjusted to 8 with a saturated Na2CO3 solution. The resulting precipitate is filtered and washed with water. (5-Bromo-pyridine-2-yl)-thiourea (“1”) is obtained after drying in vacuo at 40° C. as a pale yellow solid in a yield of 63%. HPLC (method C): 1.43 min; LC-MS (method A): 1.062 min, 231.95 (MH+).