tert-butyl (5S,8R,11S,14S,17S,20S)-11-benzyl-14-(2-(tert-butoxy)-2-oxoethyl)-5-(4-hydroxybenzyl)-17,20-diisopropyl-8-methyl-3,6,9,12,15,18,21-heptaoxo-1-phenyl-2-oxa-4,7,10,13,16,19,22-heptaazatetracosan-24-oate

Asp(OtBu)-Val-Val-Gly-OtBu

Z-Val-Val-Gly-OtBu

Z-Asp(OtBu)-Val-Val-Gly-OtBu

H-Ala-Val-Gly-OBut