143150-92-9

17899-48-8

143150-92-9

5-Methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-amine (12) (600.0 g, 3.545 mol) was used as a raw material and suspended in water (6.0 L). 48% hydrobromic acid (4.2 L) was added slowly and dropwise at 0 to 15 °C. Subsequently, a solution of sodium nitrite (367.2 g, 3.56 mol) in water (1.8 L) was added dropwise over 1.5 to 5 hours. After the dropwise addition, the reaction mixture was heated to 30°C and stirred continuously for 24 hours. After completion of the reaction, the reaction mixture was neutralized with 5N aqueous sodium hydroxide solution (6.0 L) to a strong base (pH = 12.5). Then, the aqueous layer was extracted with toluene (12.0 L and 6.0 L) in two batches. The toluene layers were combined and dried by adding anhydrous sodium sulfate (1202.0 g). After filtration to remove insoluble matter, the mother liquor was concentrated under reduced pressure at 40 °C to afford the target product 2-bromo-5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine (11a) (557.6 g, 67.5% yield). The product was characterized by 1H-NMR (CDCl3): δppm 3.58-3.57 (t, 3H, J = 1.8Hz), 2.92-2.87 (m, 2H), 2.81-2.76 (m, 2H), 2.49 (s, 3H).