Ethyl 2,2-dimethyl-2,3-dihydrobenzofuran-4-carboxylate (10 g, 45 mmol) was used as starting material, which was mixed with a solution of sodium hydroxide (16.3 ml, 10N, 163 mmol) in ethanol (50 ml) and heated to reflux for 2 hours. Upon completion of the reaction, the mixture was concentrated under vacuum and subsequently diluted with water and acidified with 12N hydrochloric acid to the appropriate pH. The precipitate produced after acidification was collected by filtration and dried in air to give 2,2-dimethyl-2,3-dihydrobenzofuran-4-carboxylic acid (8.6 g, 100% yield).
