Uses
6-Bromo-2,3-dihydrobenzofuran is used in the preparation of 2-alkylamino nicotinamide analogs as orally active ghrelin receptor (ghrelinR) inverse agonists.
Synthesis
GENERAL STEPS: A hexane solution of 1.6 M n-butyllithium (21.84 mL, 34.94 mmol) was slowly added dropwise to a solution of tetrahydrofuran (THF, 200 mL) of 1,4-dibromo-2-(2-bromoethoxy)benzene (10.45 g, 29.12 mmol) under argon protection, maintaining the reaction temperature at -78 °C. The reaction was carried out by stirring the reaction mixture for 30 minutes. After dropwise addition, the reaction mixture was continued to be stirred at -78 °C for 30 min, followed by warming up to 0 °C and stirring for 2 hours. After completion of the reaction, the mixture was poured into ice water and the pH was adjusted to 3 with 2 N hydrochloric acid. next, the aqueous phase was extracted three times with a solvent mixture of ethyl acetate/hexane (3:1, v/v). The organic layers were combined, washed with saturated brine, dried over anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. The resulting crude product was purified by silica gel column chromatography using gradient elution (2%→8% ethyl acetate/hexane) to afford 6-bromo-2,3-dihydrobenzofuran (4.57 g, 22.96 mmol, 79% yield) as a white solid.
References
[1] Patent: WO2009/7399, 2009, A1. Location in patent: Page/Page column 86
[2] Patent: EP2862571, 2015, A1. Location in patent: Paragraph 0146; 0147
[3] Patent: US2015/166559, 2015, A1. Location in patent: Paragraph 0200; 0201
[4] Patent: TW2016/2105, 2016, A. Location in patent: Paragraph 1108
[5] Patent: US2010/16297, 2010, A1. Location in patent: Page/Page column 34
