Synthesis
General procedure: In a 10 mL round-bottomed flask equipped with a magnetic stirrer, 5-bromo-8-methoxy-3,4-dihydronaphthalen-1(2H)-one (82 mg, 0.32 mmol), anhydrous methanol (4 mL), and triethylamine (1 drop) were added sequentially. Subsequently, a palladium/carbon catalyst (8 mg, 0.032 mmol) was added to the reaction system and the air within the reaction system was replaced with nitrogen. A hydrogen balloon was connected to the reaction system and the reaction mixture was stirred overnight at room temperature. Upon completion of the reaction, the reaction mixture was filtered through diatomaceous earth and the filter cake was washed with methanol (3 x 10 mL). The filtrate was concentrated under reduced pressure and the resulting crude product was purified by column chromatography (silica gel as stationary phase and hexane-ethyl acetate = 9:1 as eluent) to afford the brown oily target product 8-methoxy-α-tetralone (54 mg, 96% yield). The product characterization data were as follows: IR (ATR, cm-1): 2943, 1677, 1563, 1280, 1067. 1H NMR (300 MHz, CDCl3): δ 7.39 (dd, J = 8.0 Hz, 1H, H-6), 6.79 (d, J = 8.0 Hz, 1H, H-7), 6.70 (d, J = 8.0 Hz. 1H, H-5), 3.84 (s, 3H, OMe), 2.93 (dd, J = 6.3 Hz, 2H, H-4), 2.69 (dd, J = 6.3 Hz, 2H, H-2), 2.10 (dd, J = 6.3 Hz, 2H, H-3).13C NMR (75 MHz, CDCl3): δ 197.5 (C-1), 160.0 (C-8), 2.10 (C-8), 2.10 (C-8), 1.0 (C-8), 1.0 (C-8), 1.0 (C-8), 1.0 (C-8), 2.10 (C-8) 160.0 (C-8), 146.8 (C-10), 135.4 (C-6), 123.6 (C-9), 121.1 (C-5), 110.2 (C-7), 55.9 (OMe), 40.7 (C-2), 31.5 (C-4), 22.1 (C-3). Mass spectrum (MS): m/z (%) = 176 (100) [M+], 91 (28), 77 (40). High Resolution Mass Spectrometry (HRMS, ESI): m/z [M+H]+ Calculated value C11H12O2: 177.0910; measured value: 177.0910.
References
[1] Organic Preparations and Procedures International, 2010, vol. 42, # 5, p. 499 - 502
[2] Synthesis (Germany), 2016, vol. 48, # 13, p. 2050 - 2056
[3] Tetrahedron, 1980, vol. 36, # 17, p. 2513 - 2519
