Methanol → (S)-4-Benzyl-2-oxazolidinone

Participants

Reaction Steps

The following experiment was done in a fume hood. Phosgene ("ca" 150 mL) in toluene (200 mL) was added dropwise over 1 h to a mechanically stirred mixture of (S)-phenylalaninol, prepared as described above, (79.1 g, 0.52 mol), toluene (900 mL), and aqueous sodium hydroxide (12.5% w/v, 1300 mL) that was cooled in an ice-bath. The reaction was monitored by TLC (silica, 1:19 methanol--chloroform) and found to be complete 30 min after the end of the addition. The cooling-bath was removed and the mixture was stirred overnight. The phases were separated and the aqueous layer was extracted with ethyl acetate (2×150 mL). The extracts and the toluene layer were combined, dried (MgSO4), and evaporated to afford a solid residue. This material was dissolved in the minimum volume of boiling ethyl acetate, and hexane was added until the solution just became turbid. The solution was allowed to cool to room temperature and was then kept overnight in a refrigerator. Filtration afforded 19 as large, colorless crystals (80 g, 86%): mp 87°-89° C. (lit.2 87°-88.5° C.).

Provenance & Evidence