21344-28-5

21344-24-1

General procedure for the synthesis of 5-bromothieno[2,3-b]pyridine from 5-aminothieno[2,3-b]pyridine: In Example 16E, 5-aminothieno[2,3-b]pyridine (1.35 g, 9.0 mmol) was reacted with isoamyl nitrite (Aldrich, 2.10 g, 18.0 mmol) and copper(II) bromide ( Aldrich, 4.03 g, 18.0 mmol) in acetonitrile (20 mL) at room temperature overnight. Upon completion of the reaction, the reaction was quenched with saturated ammonium chloride solution (20 mL) and subsequently extracted with ethyl acetate (3 x 50 mL). The organic phases were combined, washed with brine (2 x 30 mL) and concentrated. The residue was purified by silica gel column chromatography (eluent: ethyl acetate/hexane, v/v 80/20, Rf = 0.80) to afford 5-bromothieno[2,3-b]pyridine (1.03 g, 53.0% yield). The product was confirmed by 1H NMR (300 MHz, CDCl3): δ 8.61 (d, J=2.03 Hz, 1H), 8.21 (d, J=2.37 Hz, 1H), 7.58 (d, J=6.10 Hz, 1H), 7.22 (d, J=6.10 Hz, 1H). Mass spectra (DCI/NH3) showed m/z 214 (M+1)+ and 216 (M+1)+.