12-Amino-15,18,21,24,27-pentakis(4-(((((benzyloxy)carbonyl)amino)acetyl)amino)butyl)-3,6,13,16,19,22,25-heptaoxo-1-phenyl-2-oxa-4,7,14,17,20,23,26-heptaazaoctacosan-28-oic acid AIDS-144911 AIDS144911 NSC668436