99% |
With sodium tetrahydroborate; ethanol; for 2h;Reflux; |
Ethyl-4-acetylbenzoate (550 mg, 2.86 mmol) was dissolved in ethanol (13 mL) and treated with sodium borohydride (10% on basic alumina, 300 mg). This suspension was heated to reflux for 2 hrs, then cooled to room temperature and filtered. The ethanol was removed by rotary evaporation; the residue was taken up in ethyl acetate and washed sequentially with IN HCl and brine, and dried over sodium sulfate. The solvent was removed under reduced pressure to yield racemic 4-(l-hydroxy-ethyl)-benzoic acid methyl ester as a colorless oil, 549 mg (99%). 1H NMR (300 MHz, CDCl3): 58.02 (d, J= 8.0 Hz, 2 H), 7.42 (d, J= 8.0 Hz, 2 H), 4.94 (q, J= 6.5 Hz, 1 H), 4.36 (q, J= 6.5 Hz, 2 H), 1.51 (d, J = 8.5 Hz, 3 H), 1.37 (t, J= 7.3 Hz, 3 H). LC-MS m/z = 195 [C10H12O3 + H]+. |
99% |
With Na(1+)*C12H33AlNO4Si2(1-); In tetrahydrofuran; toluene; at 0℃; for 1h;Inert atmosphere; |
General procedure: A dry and argon-flushed flask, equipped with a magnetic stirring bar and septum, was charged with 4-acetylbenzaldehyde (1.0 mmol) and THF (10 mL). After cooling to 0 C, the modified Red-Al (0.5 M, 2.2 mL in THF) was added dropwise and the mixture was stirred for 1 h at 0 C. The reaction was quenched with 1 N aqueous HCl (10 mL) and the product was extracted with diethylether (10 mL). The organic layer was dried over anhydrous magnesium sulfate, the solvent was removed under reduced pressure and the crude residue was purified by column chromatography (SiO2, ethyl acetate/hexane, 1:5 v/v) to affording the desired alcohol (123 mg, 83% yield). |
88% |
With potassium diisobutyl-tert-butoxyaluminum hydride; In tetrahydrofuran; at 0℃; for 1h;Inert atmosphere; |
General procedure: A dry and argon-flushed flask, equipped with a magnetic stirring bar and a septum, was charged with dicarbonyl compound (1.0 mmol) and 10 mL THF. After cooling to 0C, PDBBA (1.3 mmol) was added dropwise and stirred for 1h at same temperature. The reaction was stopped by the aqueous 1N HCl (10mL) and extracted with diethyl ether (2×10mL). The combined organic layers were dried over MgSO4, filtered and concentrated under reduced pressure. Purification of the residue by column chromatography on silica gel afforded the desired product. |