4-Hydroxy-3-methylsulfanylbenzoic acid → 4-Hydroxymethyl-2-methylsulfanylphenol

Temperatur

60 °C

With ice-cooling, a solution of 7d (1.37 g; 7.4 mmol) in abs. tetrahydrofuran (THF; 15 ml) was added to a suspension of 95% pure LiAlH4 (0.55 g; 14 mmol) in absolute THF (10 ml) in a three-necked flask (which had been dried by heating and flushed with argon) such that there was only a moderate evolution of gas. After the addition had ended, cooling was removed and the reaction mixture was stirred at room temperature for 30 min and at 55-65° C. for a further 21 h. With ice-cooling, ice-water was added to the reaction mixture. The precipitate of Al(OH)3 was dissolved by adding 10% strength sulfuric acid, and the aqueous-acidic solution (pH 1) was extracted with diethyl ether (3×50 ml). The combined ethereal extract was extracted with 10% strength aqueous sodium hydroxide solution (2×25 ml). The combined sodium hydroxide solution was neutralized with 20% strength hydrochloric acid. The precipitate (8c) was filtered off, washed with H2O and dried. A further charge of 8c was obtained by extraction of the neutral aqueous solution with diethyl ether. The ethereal extract was washed with saturated NaCl solution, dried over Na2SO4 and concentrated: crystalline white solid.