731018-54-5

170961-15-6

731018-54-5

General procedure for the synthesis of N-(5-fluoro-2-thiazolyl)-carbamic acid-1,1-dimethylethyl ester from tert-butyl thiazol-2-ylcarbamate as raw material: to a solution of tert-butyl thiazol-2-ylcarbamate (17.0 g, 84.9 mmol) in tetrahydrofuran (THF, 100 mL) was added slowly and dropwise to a solution of tert-butyllithium in hexanes at -78 °C (74.7 mL, 187 mmol, 2.5 mol/L). After the dropwise addition, the reaction mixture was warmed up to -10 °C within 30 min and kept at this temperature with stirring for 1 hour. Subsequently, the mixture was cooled again to -78 °C and N-fluorobenzenesulfonimide (2.362 g, 7.49 mmol) was added. The acetone-dry ice bath was removed and the reaction mixture was stirred at room temperature for 30 minutes. Upon completion of the reaction, the mixture was poured into cold water (100 mL) and extracted with ethyl acetate (20 mL x 3). The organic layers were combined, washed sequentially with 2N HCl, water and saturated brine, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: EtOAc/petroleum ether=15%) to afford N-(5-fluoro-2-thiazolyl)-carbamic acid-1,1-dimethylethyl ester as a white solid in 10.5 g (56.7% yield). The product was confirmed by NMR hydrogen spectrum (400 MHz, CDCl3): δ 12.20 (s, 1H), 6.88 (d, J = 3.6 Hz, 1H), 1.59 (s, 9H). Electrospray mass spectrometry (ESI-MS) analysis: m/z calculated value [C8H11FN2O2S]+ [M+H-56]+: 163.0; measured value: 163.0.