Synthesis
5-Cyano-2-trifluoroacetamido thiazole (3.32 g, 15 mmol) was used as raw material, and it was reacted with potassium carbonate (4.0 mL 10% w/v methanol/water (5:2) solution) for 3 hours at 20°C with stirring. After completion of the reaction, the insoluble material was removed by filtration, and the pH of the filtrate was adjusted to 7 with dilute hydrochloric acid and filtered again to remove the insoluble material. Subsequently, the filtrate was evaporated to remove volatiles. The residue was suspended in water and extracted with ethyl acetate. The organic phases were combined, washed sequentially with water and brine, dried over anhydrous magnesium sulfate and evaporated to remove the solvent. The resulting residue was treated with 20% aqueous fluoboric acid (40 mL) and heated at 70 °C for 1 hour. The reaction mixture was cooled, neutralized with solid sodium bicarbonate at 0 °C and extracted with ethyl acetate. The organic phases were combined, dried over anhydrous magnesium sulfate and evaporated to remove volatiles to give 2-amino-5-cyanothiazole (1.79 g, 95% yield) as a final solid product. The product was confirmed by NMR hydrogen spectrum (400.13 MHz): δ 7.83 (1H, s), 8.12 (2H, s); mass spectrum (m/z): 125 [MH]+.
References
[1] Patent: WO2007/31745, 2007, A1. Location in patent: Page/Page column 102-103
[2] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1973, p. 2769 - 2772
