Acetic Acid → 4-(Isoquinolin-3-yl)phenol

Participants

Reaction Conditions

Reaction Steps

2-(4-Methoxy phenylethynyl)benzaldehyde (2.06 g, 8.73 mmol) and t-butylamine (3.83 g, 52.4 mmol) were stirred under nitrogen for 24 h at room temperature. The resulting mixture was extracted with ether and the organic layer was dried over anhydrous Na2SO4, concentrated to give the imine (2.4 g, 94%) which was used in the next step without further purification. To a solution of this imine (2.39 g, 8.2 mmol) in 100 mL anhydrous DMF was added (0.156 g, 0.82 mmol) copper(I) iodide and flushed with nitrogen. The reaction mixture was heated at 100° C. for 4 h. The mixture was cooled to room temperature, and diluted with ether (200 mL). The organic layer was washed with saturated aqueous ammonium chloride (3×100 mL). The organic layer was dried over anhydrous Na2SO4 and concentrated to give the crude compound as a dark coloured solid. Purification by column chromatography (SilicaGel 230-400 mesh; 10% ethylacetate in hexanes as eluent) afforded 3-(4-methoxyphenyl)isoquinoline (1.064 g, 55%) as a white solid. The 3-(4-methoxyphenyl)isoquinoline (1.05 g, 4.47 mmol) was suspended in 30 mL hydroiodic acid and 12 mL of acetic acid was added. The reaction mixture was stirred at 110° C. for 2 h, then cooled to room temperature. The precipitate formed was filtered off, washed with acetic acid (2×5 mL) and dried under vacuum to give a yellow solid. The crude compound was purified by triturating with 5% methanol in ether to give 4-isoquinolin-3-yl-phenol (0.83 g, 84%) as a white powder. MS (ES) m/z: 222.89 (M+1), 221.86 (M); Mp. 218-219° C.

Provenance & Evidence