1137142-58-5

107-20-0

37566-39-5

1137142-58-5

The general procedure for the synthesis of 2-bromoimidazo[2,1-b][1,3,4]thiadiazole from chloroacetaldehyde and 2-amino-5-bromo-1,3,4-thiadiazole was as follows: 1. Preparation of Intermediate 3: To an aqueous (27 mL) suspension of 2-amino-5-bromo-1,3,4-thiadiazole (1.65 g, 9.15 mmol) was added a 50% wt aqueous chloroacetaldehyde solution (1.7 mL). 2. The reaction mixture was stirred under reflux conditions for 10 hours. 3. Subsequently, 1.5 equivalents of chloroacetaldehyde (1.7 mL) was added again and stirring was continued until the feedstock was completely consumed (approximately 20 hours). 4. Upon completion of the reaction, the mixture was cooled to room temperature and neutralized with saturated aqueous sodium bicarbonate. 5. The reaction mixture was extracted with dichloromethane (3 x 30 mL) and the organic layers were combined. 6. The organic layer was dried with anhydrous sodium sulfate, followed by evaporation of the solvent under reduced pressure. 7. The crude product was ground with ether to give 2-bromoimidazo[2,1-b][1,3,4]thiadiazole as a white solid. 8. The mother liquor was further purified by fast chromatography (Biotage?, eluent: ethyl acetate/hexane, 3:7 to 7:3) to obtain another batch of the target compounds in a total yield of 20%. Product characterization: 1H NMR (300 MHz, CDCl3): δ 7.64 (s, 1H), 7.24 (s, 1H). MS (ES+) m/z: 204 (M + H)+ (MW: 204.05).