The general procedure for the synthesis of 3-bromothieno[2,3-b]pyridine from thieno[2,3-b]pyridine was as follows: 2.30 g of thieno[2,3-b]pyridine (17 mmol), 1.43 g of NaHCO3 (17 mmol), 4.44 g of K2HPO4 (25.5 mmol) and 2.66 g of MgSO4 (22.1 mmol) were were placed in a reaction flask and 80 mL of dichloromethane was added. The reaction mixture was heated to reflux with continuous stirring. 1.05 mL of bromine (20.4 mmol) was slowly added dropwise to the reaction system and stirring was continued overnight. Upon completion of the reaction, the cooled reaction mixture was extracted with dichloromethane and water to separate the organic phase. The organic phase was dried with anhydrous Na2SO4 and subsequently concentrated under reduced pressure to remove the solvent. The crude product was purified by silica gel column chromatography (eluent: hexane/ethyl acetate = 3:1) to afford 1.76 g of 3-bromothieno[2,3-b]pyridine in 48% yield. The product was characterized and confirmed by mass spectrometry (m/e): 215 (M+1) and 1H-NMR (CDCl3): δ 8.67 (m, 1H), 8.13 (m, 1H), 7.59 (s, 1H), 7.45 (m, 1H) ppm.
![Thieno[2,3-b]pyridine (8CI,9CI)](/CAS/GIF/272-23-1.gif)
![3-Bromothieno[2,3-b]pyridine](/CAS/GIF/28988-21-8.gif)