Abstract Trityl-glycyl-ϵ-CBO-L-lysine is condensed with L-prolyl-L-valine methyl ester and, after amidification and splitting of the trityl group, glycyl-ϵ-CBO-L-lysyl-L-prolyl-L-valylamide is obtained. This is condensed with ditrityl-L-histidyl-L-phenylalanyl-L-arginyl-L-tryptophane
