2-Methyl-2-butene → 2-methoxy-5-(trifluoromethoxy)benzoic Acid

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Reaction Steps

According to the method of Heterocycles, 16, 2091 (1981), combine 2-methoxy-5-trifluoromethoxybenzaldehyde (0.58 g, 2.65 mmol) and 2-methylbut-2-ene (37 mL) in t-butanol (16 mL). Add dropwise a solution of sodium dihydrogen phosphate hydrate (0.92 g) and sodium chlorite (0.42 g, 4.7 mmol) in water (10 mL). After 4 hours, adjust the pH of the reaction mixture to about 8 to 9 using a 1M aqueous sodium hydroxide solution. Evaporate the reaction mixture in vacuo at about ambient temperature to remove most of the t-butanol. Add water (40 mL) and extract three times with hexane (10 mL). Adjust the pH of the aqueous layer to about 1 using a 1M aqueous hydrochloric acid solution and extract five times with diethyl ether. Combine the organic layers, dry over Na2SO4, filter, and evaporate in vacuo to give a residue. Chromatograph the residue on silica gel eluting with 1/1 ethyl acetate/hexane containing 0.5% acetic acid to give 2-methoxy-5-trifluoromethoxybenzoic acid: Rf =0.34 (silica gel, 1/1 ethyl acetate/hexane containing 0.5% acetic acid).

Provenance & Evidence