Sulfuric Acid → (S)-Methyl 2-(6-hydroxy-2,3-dihydrobenzofuran-3-yl)acetate

Participants

Reaction Conditions

Reaction Steps

To a solution of [(3S)-6-hydroxy-2,3-dihydro-1-benzofuran-3-yl]acetic acid (1R)-1-phenylethylamine salt (1.0 g) in methanol (3 mL)-toluene (8 mL) was added concentrated sulfuric acid (0.412 mg), and the mixture was stirred at 60° C. for 2 hr. The mixture was concentrated, toluene (5 mL) was added, and the mixture was concentrated again. To the residue were added toluene (5 mL), tetrahydrofuran (8 mL) and 1N hydrochloric acid (5 mL) to perform an extraction operation. The organic layer was washed with water, 5% aqueous sodium bicarbonate and water, and concentrated, and the residue was dissolved in toluene (8 mL). The activated carbon (100 mg) was added, and the mixture was stirred at room temperature for 30 min. After filtration, the filtrate was concentrated. The obtained crude product was dissolved in toluene (2 mL), seed crystal was added, and the mixture was stirred at room temperature for 16 hr. n-Heptane (6 mL) was added, and the mixture was stirred at room temperature for 5 hr and at 0° C. for 1 hr. The precipitated crystals were collected by filtration, and dried at 50° C. to give the title compound (554 mg) as white crystals. 99.7% ee.

Provenance & Evidence