L-Phenylalanine → Benzyloxycarbonyl-L-phenylalanine

Participants

Reaction Conditions

Reaction Steps

L-Phenylalanine (5 g, 30 mmol) was dissolved in a solution (200 ml) containing equal proportions of tetrahydrofuran and 5% NaHCO3, and chilled to 0° C. Benzyl chloroformate (4.7 ml, 33 mmol) was dissolved in tetrahydrofuran (10 ml) and added slowly to the amino acid solution over a period of 1 hour. The pH was continually adjusted to 8.5 by the addition of 5% Na2CO3 and the reaction was allowed to proceed at room temperature overnight. The organic solvent was removed under reduced pressure and the resulting aqueous solution was poured slowly into chilled, concentrated HCl (50 ml). The product precipitated and was extracted into ethyl acetate (200 ml). It was washed with 5% NaHSO4 and dried over magnesium sulphate. Recrystallisation was from ethyl acetate/hexane. Yield 8.29 g (91%), m.p. 83°-83° C. (Lit. 82°-84° C., Berger et al., 1973). The product was homogeneous as judged by tlc in chloroform/methanol (4:1) (Rf 0.500) or chloroform/methanol (1:1) (Rf 0.364).

Provenance & Evidence