2-Chlorothiazolo[4,5-b]pyrazine

Synthesis

The general procedure for the synthesis of 2-chlorothiazolo[4,5-b]pyrazine from the compound (CAS: 87444-22-2) was as follows: preparation of intermediate 2: 2-chloro[1,3]thiazolo[4,5-b]pyrazine [1,3]thiazolo[4,5-b]pyrazine-2(3H)-thione (4.36 g, 25.8 mmol) was dissolved in dichloromethane ( CH2Cl2, 60 mL) and sonicated for 5 min. Under continuous stirring, thionyl chloride (60 mL) was added and the reaction mixture was heated to 40 °C and maintained at this temperature for 16 hours. Upon completion of the reaction, the mixture was cooled to room temperature and subsequently placed in an ice bath. Water (250 mL) was slowly added, followed by slow addition of 4N sodium hydroxide (NaOH, 550 mL) solution. The aqueous phase was extracted with ethyl acetate (EtOAc, 2 x 1800 mL), and the organic phases were combined, dried and concentrated to afford the target product 2-chlorothiazolo[4,5-b]pyrazine (2.63 g, 53% yield). The structure of the product was confirmed by 1H NMR (500 MHz, DMSO-d6) and mass spectrometry (ESI): 1H NMR (500 MHz, DMSO-d6) δ 8.84 (d, J = 2.5 Hz, 1H), 8.75 (d, J = 2.5 Hz, 1H); MS (ESI) m/z: [M + H]+ calculated value 170.97, measured value 172.10.

References

[1] Patent: US2009/258854, 2009, A1. Location in patent: Page/Page column 28