[(Benzyl-{2-[benzyl-(2-carboxymethoxy-acetyl)-amino]-ethyl}-carbamoyl)-methoxy]-acetic acid 、
1,7-dibenzyl-4-phenyl-1,4,7-triazaheptane 以
二氯甲烷 为溶剂,
以58%的产率得到4,7,13,19-Tetrabenzyl-16-phenyl-1,10-dioxa-4,7,13,16,19-pentaaza-cyclohenicosane-3,8,12,20-tetraone