5-[2-(acetylamino)-4-methyl-1,3-thiazol-5-yl]thiophene-2-sulfonyl chloride, prepared in Step II (200 mg; 0.59 mmol; 1 eq) is dissolved in anhydrous DCM (10 ml). The reaction is put under nitrogen. Prop-2-ynylamine (0.08 ml; 1.19 mmol; 2 eq), diisopropylethylamine (0.61 ml; 3.56 mmol; 6 eq) are added successively and the reaction mixture is stirred for 3 hours at room temperature. Solvents are evaporated and the resulting crude product is purified by preparative HPLC. Compound (1) is isolated as a beige powder (25 mg; 12%).
