Ammonium Chloride → 5-Bromo-2,3-dihydro-1-benzofuran

Participants

Reaction Steps

5,7-Dibromo-2,3-dihydrobenzo[b]furan (see WO 02/070020) (3.0 g) in diethyl ether was cooled to −78° C. under argon atmosphere, and thereto was added dropwise n-butyl lithium (2.44 M hexane solution, 5.09 ml). The mixture was stirred at the same temperature for 30 minutes, and poured into a saturated aqueous ammonium chloride solution. The mixture was extracted with diethyl ether, and dried over magnesium sulfate. The solvent was evaporated under reduced pressure to give 5-bromo-2,3-dihydrobenzo[b]furan (2.0 g) as pale yellow crystals, which was used in the subsequent step without further purification. (2) The above 5-bromo-2,3-dihydrobenzo[b]furan and thiophene-2-boronic acid were treated in a manner similar to Reference Example 20-(1) to give the desired 2-(2,3-dihydro-5-benzo[b]furanyl)thiophene as pale yellow crystals. APCI-Mass m/Z 203 (M+H).

Provenance & Evidence