HCID 22858886, compound → HCID 10798722, compound

Participants

Reaction Steps

To a solution of ethyl N-acetyl-(±)-α-methylleucinate (250.0 mg, 1.16 mmol) in 70 mL of 50 mM sodium phosphate buffer pH 7.5 is added carboxypeptidase Y from Bakers Yeast (10.4 mg of protein). After 120 h, 50% conversion is observed by HPLC (C18 column, 210 nm detection, amido acid tR =8.1 rain and amido ester tR =10.7 min). The reaction is extracted with 3×25 mL chloroform. The combined extracts are dried with magnesium sulfate and concentrated in vacuo to yield ethyl (R)-N-acetyl-α-methylleucinate (120 mg, 0.557 mmol, 48%). A portion of this (R)-α-methyl amido ester (70 mg, 0.325 mmol) is refluxed in 50 mL 6N HCl for 2 h then concentrated in vacuo to afford (R)-α-methylleucine hydrochloride (70 mg). The enantiomeric excess of the amino acid is determined by HPLC analysis ((D)-Penicillinamine column from Phenomonex, detection 254 nm, (S)-enantiomer tR =4.6 min and (R)-enantiomer tR =7.4 min) to be >98% (R)-enantiomer.

Provenance & Evidence