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With sodium borohydrid; In methanol; water; toluene; |
Method A 4,4-Dimethyl-2-tetralone To a stirred suspension of sodium borohydride (3.5 g, 93 mmoles) in dry methanol (50 ml) at 0 C. under a nitrogen atmosphere was added a solution of <strong>[2979-69-3]4,4-dimethyl-1-tetralone</strong> (10 g, 57.4 mmoles) in dry methanol:toluene (1:3) dropwise over a 45 minute period. After this time the mixture was allowed to warm to room temperature, and then two volumes of water were added. After stirring for 1 hour, the organic layer was separated, dried over magnesium sulfate, filtered, and evaporated under reduced pressure to leave a light yellow oil. This was purified by silica gel column chromatrography eluding with ethyl acetate:hexane (1:9) to give 1,2,3,4-tetrahydro-4,4-dimethyl-1-naphthol as a colorless oil. (9.89 g, 98%). |
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With sodium tetrahydroborate; In tetrahydrofuran; methanol; at 20℃; for 0.5h; |
To a suspension of sodium borohydride (3.12 g, 82.5 mmol) in 4:1 THF:MeOH (250 mL) was added 4,4-dimethyl-3,4-dihydronaphthalen-l(2H)-one (13.1 g, 75.0 mmol) dropwise over 15 minutes. The mixture was stirred at ambient temperature for 15 minutes and was quenched with 1M NaOH (50 mL). After stirring for 15 minutes, the mixture was concentrated and the aqueous residue was diluted with 1M NaOH (50 mL) and H20 (50 mL). The mixture was extracted with hexanes (3X) and the combined extracts washed with H20 and saturated NaCl. The organic portion was dried over MgSCVactivated charcoal, filtered through packed Celite and concentrated to provide the crude product as a faint yellow syrup after drying in vacuum (11.8 g, 89%). 1H NMR (CDC13) delta 7.41 (dd, J=7.6, 1.6 Hz, 1H), 7.33 (dd, J=7.9, 1.5 Hz, 1H), 7.25 (dt, J=7.3, 1.6 Hz, 1H), 7.18 (dd, J=7.5, 1.5 Hz, 1H), 4.72 (dd, J=5.5, 5.1 Hz, 1H), 2.11-2.03 (m, 1H), 1.93-1.83 (m, 2H), 1.73 (br s, 1H), 1.63-1.57 (m, 1H), 1.33 (s, 3H), 1.24 (s, 3H) ppm. |
| 1.31 g |
With sodium tetrahydroborate; In methanol; at 0℃; |
General procedure: To a solution of <strong>[2979-69-3]4,4-dimethyl-1-tetralone</strong> (8.64 mmol, 1.51 g) in MeOH wasadded NaBH4 (106 mg, 2.81 mmol) at 0 C. The mixture was stirred until completionof the reaction (TLC). Following full consumption of substrate, the reaction wasquenched with H2O and extracted with Et2O (3 times). The combined organic layerswere dried over anhydrous MgSO4 and filtered. The solvent was removed underreduced pressure. The residue was chromatographed on silica gel (hexane / AcOEt =3:1) to give the 4,4-dimethyl-1-tetranol (1.31 g, % yield). The NMR data are inagreement with those previously reported in literature14. 1H NMR (CDCl3, 500 MHz): 7.42 (d, J = 8.0 Hz, 1H), 7.34 (d, J = 8.0 Hz, 1H), 7.26 (m, 1H), 7.19 (m, 1H), 4.74(m, 1H), 2.11-2.05 (m, 1H), 1.93-1.85 (m, 1H), 1.68 (d, J = 5.7 Hz, 1H), 1.64-1.58 (m,1H), 1.34 (s, 3H), 1.25 (s, 3H). 13C NMR (CDCl3, 125 MHz): 145.6, 137.7, 128.2,127.9, 126.6, 125.9, 68.8, 34.3, 33.9, 31.4, 31.3, 28.8. |
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