Dicyclohexylcarbodiimide → Nalpha-Benzyloxycarbonyl-D-alanyl-L-leucine methyl ester

Participants

Reaction Conditions

Reaction Steps

Nα-Benzyloxycarbonyl-D-alanine, 8.92 g., 40 mmol, L-leucine methyl ester hydrochloride, 7.28 g., 40 mmol and 1-hydroxybenztriazole, 5.4 g., 40 mmol are dissolved in 100 ml. of dimethylformamide and the solution stirred and cooled to -10° C. Triethylamine, 5.6 ml., 40 mmol, is added and after fifteen minutes the solution is treated with 8.6 g., 42 mmol, of dicyclohexylcarbodiimide and stirred for 2 to 3 hours in a cooling bath and then to room temperature overnight. The mixture is filtered and the filtrate evaporated. The residue is dissolved in ethyl acetate and washed with 5% sodium bicarbonate solution, dilute hydrochloric acid and saturated sodium chloride solution, dried over magnesium sulfate and evaporated. The residue is crystallized twice from etherpetroleum ether, 12.88 g.; m.p. 65°-68° C.

Provenance & Evidence