Sulfuric Acid → Benzenepropanoic acid, beta-(benzoylamino)-alpha-hydroxy-, methyl ester, (alphaR,betaS)-

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Reaction Steps

To a suspension of 15.0 g (55.5 mmol, thus only 67%) (2RS,3S)-2-Amino-3-hydroxy-2-phenylpropionic acid (from Example 3) in 250 ml methanol one carefully adds dropwise at room temperature 5 ml of concentrated H2SO4 and heated for 6 hours under reflux. 50 ml H2 0 are added and the pH adjusted to 6.8 with 50% NaOH at +5° C. Subsequently the methanol is removed by vacuum distillation, the mixture cooled to +5° C. and reacted with 10 g (120 mmol) NaHCO3 and 8.4 ml (72 mmol) benzoylchloride are added dropwise over 20 minutes. After further stirring for 2 hours the precipitated raw product is vacuum filtered, recrystallized out of 150 ml of methanol and dried to a colorless product at 50° C. in a vacuum drying vessel.

Provenance & Evidence