Synthesis
The general procedure for the synthesis of 5-bromo-2-mercaptopyridine from 2-hydroxy-5-bromopyridine was carried out as follows: Lawesson's reagent (2.32 g, 5.74 mmol) was added batchwise to an anhydrous toluene (50 mL) suspension of 5-bromo-2(1H)-pyridone (2 g, 11.5 mmol) and the reaction was carried out under nitrogen protection. The reaction mixture was heated to reflux for 1 h and then cooled to room temperature. The product precipitated during cooling was collected by filtration and dried under high vacuum to afford 5-bromo-2-mercaptopyridine (2.1 g, 96% yield), which could be used in subsequent steps without further purification.
References
[1] Patent: US2012/309796, 2012, A1. Location in patent: Page/Page column 25
[2] Patent: WO2007/39580, 2007, A1. Location in patent: Page/Page column 36
[3] Patent: WO2007/39578, 2007, A1. Location in patent: Page/Page column 42
[4] Patent: WO2007/39581, 2007, A1. Location in patent: Page/Page column 32
