A stirred mixture of 2-{1-[(6-chloroimidazo[2,1-b][1,3]thiazol-5-yl)sulfonyl]-1H-indol-3-yl}ethylamine hydrochloride, 417 mg, 1.00 mmol) in dichloromethane and triethylamine (0.40 mL, 3.0 mmol) is treated with catalytic 4-dimethylaminopyridine (DMAP) (˜5 mg) at room temperature under nitrogen. The heterogeneous mixture is treated with acetic anhydride (0.30 mL, 3.2 mmol) and the reaction becomes homogeneous. After 16 h, the reaction is treated with saturated aqueous NaHCO3 (8 mL) for 0.3 h and then extracted with dichloromethane. The extracts are combined, dried over MgSO4 and concentrated in vacuo to a foam. The foam is treated with 20:80 ethyl acetate:hexane and concentrated in vacuo to a solid. This is triturated with ether and filtered. The filtercake is dried to afford the title product as a white solid, 389 mg (92% yield), mp 150-152° C., characterized by CHN elemental analysis and 1H NMR.
