4-Hydroxy-3,5-dimethylbenzoic acid → 3,5-dimethyl-N-[3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]benzyl]-4-hydroxybenzamide

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a solution of 3,5-dimethyl-4-hydroxybenzoic acid (1.53 g, 9.2 mmol) in dichloromethane (30 mL) at 0° C. was added benzotriazol-1-yl-oxy-tris(dimethylamino)phosphonium hexafluorophosphate (4.45 g, 10 mmol), 3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]benzenemethanamine (Example 70; 3.28 g, 13.8 mmol), followed by diisopropylethylamnine (4.9 mL, 27.6 mmol) slowly dropwise. After stirring 1 h, the reaction was warmed to 25° C. and stirred for 1 h. The solvent was removed under reduced pressure and the residual oil was diluted with ethyl acetate (100 mL) and washed with 1N hydrochloric acid solution (2×25 mL), saturated aqueous sodium bicarbonate solution (2×25 mL), water (25 mL) and brine (25 mL). The organic layer was dried (MgSO4), filtered, evaporated and flash chromatographed (silica gel, 20-30% ethyl acetate in petroleum ether) to give 3,5-dimethyl-N-[3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]benzyl]-4-hydroxybenzamide (3.1 g, 87% yield) as an off-white foam.

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