(S)-(5S,6S,8S)-5,8-Dibenzyl-12,12-dimethyl-3,10-dioxo-1-(thiazol-5-yl)-2,11-dioxa-4,9-diazatridecan-6-yl 2-(3-((2-Isopropylthiazol-4-yl)methyl)-3-methylureido)-3-methylbutanoate