Hydrochloric Acid → 5-chloro-2-(4-chlorophenyl)-1H-Indole

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Reaction Steps

n-Butyllithium (1.6M in hexanes, 127 mL, 203 mmol) was added dropwise to a stirred, cooled (−10° C.) solution of 4-chloro-N-(4-chloro-2-methylphenyl)benzamide (Description 27, 27.1 g, 97 mmol) in tetrahydrofuran (600 mL). The mixture was allowed to warm to room temperature and stirred overnight. The mixture was cooled to 0° C. and further n-butyllithium (1.6M in hexanes, 30 mL, 483 mmol) was added dropwise. The mixture was stirred at room temperature for 2 h., then hydrochloric acid (2.5M, 200 mL) was added. The mixture was stirred at room temperature overnight, then extracted with ethyl acetate. The combined organic fractions were dried (MgSO4) and the solvent was evaporated under reduced pressure. The residue was purified by flash column chromatography on silica gel, eluting with isohexane/EtOAc (85:15), to give the title compound (3.6 g, 14%). 1H NMR (360 MHz, CDCl3) δ 8.30 (1H, br s), 7.57 (3H, m), 7.42 (2H, d, J 9.1 Hz), 7.30 (1H, d, J 8.6 Hz), 7.15 (1H, dd, J 8.6, 2.0 Hz) and 6.74 (1H, s).

Provenance & Evidence