Synthesis
General procedure for the synthesis of 6-bromo-1H-indene from 5-bromoindanone: Sodium borohydride (1.1 g, 0.029 mol) was added in three batches to a solution of 5-bromoindan-1-one (3.09 g, 0.0136 mol; CAS No. 34598-49-7) in methanol (25 mL) under argon protection at a reaction temperature of 0 °C. After 2 hours of reaction, the reaction mixture was partitioned between ethyl acetate and water. The organic layer was separated, washed sequentially with water and brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give an amber solid (3.16 g). The solid (1.58 g) was dissolved in ethylene glycol (63 mL) and 20% by volume of aqueous sulfuric acid (63 mL) was added. The reaction mixture was heated to 75 °C, kept for 2 h, then cooled to room temperature and extracted with dichloromethane (2 times). The organic layers were combined, washed with saturated aqueous sodium bicarbonate, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography using hexane as eluent to afford the target product 6-bromo-1H-indene (0.76 g, 52% yield) as a clear liquid.
References
[1] Patent: WO2009/67202, 2009, A1. Location in patent: Page/Page column 195
[2] European Journal of Medicinal Chemistry, 2017, vol. 141, p. 101 - 112
[3] Organic and Biomolecular Chemistry, 2003, vol. 1, # 8, p. 1298 - 1307
[4] Bioorganic and Medicinal Chemistry Letters, 2002, vol. 12, # 5, p. 827 - 832
[5] Bioorganic and Medicinal Chemistry Letters, 1999, vol. 9, # 12, p. 1657 - 1662
