[Synthesis]
Under argon protection, TBAF (157 mg, 0.60 mmol) was dissolved in DMA (1.2 mL), followed by addition of a solution of 3-methoxy-2-(trimethylsilyl)phenyl trifluoromethanesulfonate (53 μL, 0.20 mmol) in DMA (0.8 mL). The reaction mixture was stirred at room temperature for 3 hours. Upon completion of the reaction, the reaction was quenched by the addition of water (0.1 mL). The reaction mixture was concentrated under reduced pressure and the residue was purified by fast silica gel column chromatography (eluent: ethyl acetate/hexane = 1/20 to 1/8 containing 2% dichloromethane) to afford 2-hydroxy-6-methoxyacetophenone (10, 11.3 mg, 34%), 2-(N,N-dimethyl)amino-6-methoxyacetophenone (11, 3.8 mg, 10%) and 3-methoxy- N,N-dimethylaniline (12, 1.3 mg, 5%).
2-Hydroxy-6-methoxyacetophenone (10): colorless crystals, melting point 57-57.5 °C (ethyl acetate/hexane). IR (KBr) νmax 3110, 3009, 2947, 1623, 1594, 1459 cm?1.1 1H NMR (CDCl3) δ 13.23 (1H, s), 7.33 (1H, t, J = 8.0 Hz ), 6.56 (1H, dd, J = 8.0, 1.0 Hz), 6.39 (1H, dd, J = 8.0, 1.0 Hz), 3.90 (3H, s), 2.67 (3H, s).13C NMR (CDCl3) δ 205.1, 164.6, 161.5, 136.0, 111.3, 110.7, 101.1, 55.6, 33.7.MS (EI+) m/z 83 (100), 166 (M+, 3).HRMS (EI+) calculated value of C9H10O3 (M+) 166.0624, measured value 166.0646.
2-(N,N-dimethyl)amino-6-methoxyacetophenone (11): colorless oil. ir (CHCl3) νmax 2942, 1702, 1577, 1468 cm?1. 1H NMR (CDCl3) δ 7.23 (1H, br t, J = 8.0 Hz), 6.67 (1H, br d, J = 8.0 Hz), 6.56 ( 1H, br d, J = 8.0 Hz), 3.78 (3H, s), 2.72 (6H, s), 2.50 (3H, s).13C NMR (CDCl3) δ 205.2, 156.2, 151.8, 130.2, 125.3, 111.0, 104.7, 55.8, 44.8, 31.8.MS (EI+) m/z 83 (100), 193 (M+, 0.4). HRMS (EI+) calculated value C11H15NO2 (M+) 193.1097, measured value 193.1121.
3-Methoxy-N,N-dimethylaniline (12): colorless oily substance. ir (KBr) νmax 2955, 1610, 1493, 1465 cm?1. 1H NMR (CDCl3) δ 7.15 (1H, t, J = 8.0 Hz), 6.36 (1H, dd, J = 8.0, 2.5 Hz), 6.31-6.27 (2H, m), 3.80 (3H, s), 2.94 (6H, s).13C NMR (CDCl3) δ 160.6, 151.9, 129.7, 105.7, 101.3, 99.1, 55.1, 40.6.MS (EI+) m/z 83 (100), 151 (M+, 0.4).HRMS (EI+) calculated values C9H14NO (M++H+) 152.1070, measured value 152.1055. |