Hydrochloric Acid → 1-Tetralone

Participants

Reaction Steps

To a solution of 3-(1-methylethyl)-6-(methyloxy)-3,4-dihydro-1(2H)-naphthalenone (68) (0.40 g, 1.83 mmol) in CH2CO2 (15 mL) was added a solution of bromine (0.59 g, 3.68 mmol) in CH2Cl2 (5 mL). The mixture was stirred at room temperature overnight. Volatiles were removed under vacuum at room temperature. The residue was dissolved in CH3CN (15 mL), cooled in an acetone-ice bath, DBU (0.44 g, 2.75 mmol) in CH3CN (2 mL) was added dropwise. The resulting mixture was allowed to warm up to room temperature and stirred for 1 h. 5 N HCl (1 mL) was added followed by brine (50 mL), and the mixture was extracted with CH2Cl2. The extracts were combined and washed with brine, dried over Na2SO4, filtered, and the filtrate was concentrated to give the crude product as a brown oil. The crude product was purified by flash chromatography over SiO2 with hexanes:EtOAc (25:1) to give 0.43 g (79% from tetralone) of the title compound (69) as a colorless viscous oil. 1H NMR (400 MHz, CDCl3): δ 1.32 (d, J=6.8 Hz, 6H), 3.35 (sept, J=6.8 Hz, 1H), 3.91 (s, 3H), 6.11 (s, 1H), 7.04 (d, J=2.4 Hz, 1H), 7.08 (dd, J1=9.1 Hz, J2=2.5 Hz, 1H), 7.21 (s, 1H), 8.08 (d, J=9.1 Hz, 1H).

Provenance & Evidence