Dicyclohexylcarbodiimide → Nalpha-Benzyloxycarbonyl-L-glutaminyl-L-tryptophyl-L-seryl-L-tyrosine methyl ester

Participants

Reaction Conditions

Reaction Steps

A mixture of the product from (c) above, 1.4 g. of Nα -benzyloxycarbonyl-L-glutamine, 670 mg. of 1-hydroxybenztriazole and 50 ml. of dimethylformamide is stirred and cooled to -10° C., and 0.7 ml. of triethylamine is added. After 15 minutes, it is treated with 1.2 g. of dicyclohexylcarbodiimide and stirred a few hours at -10° C., then at room temperature for two days and finally let stand an additional three days. The solution is filtered and the filtrate evaporated at 50° C. under reduced pressure. The residue is precipitated from methanol with water and then crystallized from methanol three times; m.p. 245°-248° C.; [α]D25 -4.4° (c 1, DMF); ultraviolet in methanol, λmax 290 E11 75.7; λmax 280 E11 100.

Provenance & Evidence