Hydrochloric Acid → ethyl (3R)-3-hydroxybutanoate

Participants

Reaction Steps

A solution of 2.33 g (15.5 mmol) of L-(+)-tartaric acid in 50 ml of tetrahydrofuran (THF) was cooled in a cryostat at -20° C., and a solution of 0.5 g (3.8 mmol) of ethyl acetoacetate in THF (2 ml) was added. To the resulting solution, there was further added 0.59 g (15.5 mmol) of sodium borohydride, all at one and with stirring, and the mixture was stirred for 13 hours. The reaction mixture was cooled in an ice bath, 25 ml of 1N HCl was added, and stirring was continued for 30 minutes. After distilling off THF under reduced pressure, the aqueous layer was extracted twice with ether (50 ml and 30 ml), and the combined extract was washed first with 30 ml of a saturated aqueous solution of sodium bicarbonate and then with 30 ml of a saturated aqueous solution of sodium chloride, and then dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure from the dried solution, and the residue was purified by silica gel column chromatography, giving 0.30 g ethyl (R)-(-)3-hydroxybutanoate as a fraction of ethyl acetate:n-hexane (1:5). Its specific rotation [α]D22 was -34.1° (cl. 20, CHCl3). The synthesis yield was 59% and the optical yield was 79% e.e. (see Reference 2).

Provenance & Evidence