Lithium Hydroxide → 4-(2-Tert-butoxycarbonyl-ethyl)-3,5-dimethyl-benzoic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-(2-tert-butoxycarbonyl-ethyl)-3,5-dimethyl-benzoic acid methyl ester (10.8 g, 37.0 mmol) in ethanol (100 mL) a 2 M aq. solution of LiOH (50 mL) is added at 0° C. The turbid mixture is stirred at 0° C. for 30 min, then at rt for 4 h. The mixture is diluted with 10% aq. citric acid solution and extracted three times with diethyl ether. The combined organic extracts are dried over MgSO4, filtered and concentrated. The solid residue is suspended in diethyl ether/heptane, stirred at rt, and filtered. The slurry procedure in diethyl ether/heptane is repeated. The solid material is collected and dried under HV to give 4-(2-tert-butoxycarbonyl-ethyl)-3,5-dimethyl-benzoic acid (5.09 g) as a white crystalline powder; LC-MS: tR=0.95 min, [M+1]+=279.14; 1H NMR (CDCl3): δ 1.47 (s, 9 H), 2.30-2.40 (m, 2 H), 2.39 (s, 6 H), 2.94-3.03 (m, 2 H), 7.75 (s, 2 H).

Provenance & Evidence