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A mixture of O-(phenylmethyl)-L-serine (commercial product) (139.0 g; 0.712 mol) and NaBH4 (96%; 75 g; 1.9 mol) in dry THF (700 mL, distilled on sodium/benzophenone), under N2 atmosphere, was slowly added (1.5 hours) with a solution of I2 (181.0 g; 0.713 mol) in dry THF (350 mL) at a temperature of 0 to 15° C. When the addition was completed and the dark color had disappeared, the mixture was refluxed for 18 hours, then cooled at 0° C. and the NaBH4 excess was destroyed with cold water (30 mL), followed by 15N KOH (320 mL). When bubble evolution was no longer observed, the mixture was heated, distilling most of the organic solvent (THF). The aqueous mixture was refluxed for 6 hours, then stirred at r.t. for a further 18 hours. CHCl3 (700 mL) and Et2O (300 mL) were added thereto under strong stirring; after 15 minutes the diphasic mixture was filtered through Celite® and the separated solid was repeatedly washed with CHCl3/Et2O 3:1 (4 L). The filtered solution was concentrated, removing water by repeated azeotropical distillations with CH3CN. The crude oil (130 g) was purified twice by flash chromatography (CH2Cl2/CH3OH/NH4OH 25% (w/w) 54:40:6 to 90:9:1), thereby obtaining the desired compound (92.63 g; 0.511 mol). Yield: 72%.

1. additionWhen the addition
2. temperaturethe mixture was refluxed for 18 hours
3. customthe NaBH4 excess was destroyed with cold water (30 mL)
4. customWhen bubble evolution
5. temperaturethe mixture was heated
6. distillationdistilling most of the organic solvent (THF)
7. temperatureThe aqueous mixture was refluxed for 6 hours
8. additionCHCl3 (700 mL) and Et2O (300 mL) were added
9. filtrationafter 15 minutes the diphasic mixture was filtered through Celite®
10. washthe separated solid was repeatedly washed with CHCl3/Et2O 3:1 (4 L)
11. concentrationThe filtered solution was concentrated
12. customremoving water
13. customThe crude oil (130 g) was purified twice by flash chromatography (CH2Cl2/CH3OH/NH4OH 25% (w/w) 54:40:6 to 90:9:1)