Hydrochloric Acid → (-)-Ethyl mandelate

Participants

Reaction Steps

A solution of 1.70 g (11.3 mmol) of L-(+)-tartaric acid in 35 ml of THF was cooled in a cryostat at -20° C., and a solution of 0.5 g (2.8 mmol) of ethyl phenylglyoxylate in THF (5 ml) was added. To the resulting solution, there was further added 0.43 g (11.3 mmol) of sodium borohyride, all at once and with stirring, and the mixture was stirred for 24 hours. The reaction mixture was cooled in an ice bath, 20 ml of 1N HCl was added, and stirring was continued for 15 minutes. After distilling off THF under reduced pressure, the aqueous layer was extracted twice with ethyl acetate (30 ml and 20 ml), and the combined extract was washed first with 20 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 0.43 g of ethyl (R)-(-)-2-hydroxy-2-phenylacetate as an ethyl acetate:n-hexane fraction(1:5). Its specific rotation [α]D16 was -108.4° (cl. 12, CHCl3). The synthesis yield was 85% and the optical yield was 85% e.e (see Reference 7).

Provenance & Evidence