Trifluoroacetic acid → HCID 18631442, compound

Participants

Reaction Steps

In 10 ml of pure trifluoroacetic acid was dissolved at 0° C. 1 g (0.0032 mol) of methyl (3S,4S)-3-hydroxy-4-(N-BOC-amino)-4-phenylbutanoate partially in racemic form. After 15 min. at 0° C., the acid was rapidly evaporated off under reduced pressure wlthout heatlng. Then the vapor had disappeared, the salt so obtained was suspended in methylene chloride at 0° C. and therewere successively added 1.06 g (0.0032 mol) of BOC-Nle-ObSU, 0.620 g (0.004 mol) of HOBt and then a sufficient amount of NEM to bring the pH of the solution to 6-7. The reaction medium was heated to room-temperature in 2 h, while controling the pH, and then stirred for 12 to 15 h. The solvent was evaporated off at room-temperature using a Buchi evaporator and the peptide was extracted by means of ethyl acetate. The organic phase was then washed with 4 fractions of a dilute aqueous solution of sodium carbonate, 2 fractions of water, 4 fractions of a dilute aqueous solution of potassium hydrogenosulphate then with 2 fractions of water and only one fraction of an aqueous solution of sodium chloride. The medium was dried on magnesium sulphate and purified by chromatography on silicagel while eluting with a 1/1 mixture of methylene chloride/ethyl acetate. After triturating in an ethyl ether/hexane mixture, 0.629 g of methyl 4-(N-BOC-norleucylamino)-3-hydroxy-4-phenylbutanoate was obtained.

Provenance & Evidence