881837-39-4 17-Oxa-2,8,15-triazanonadecanoic acid,6-[[(1,1-dimethylethoxy)carbonyl]amino]-18,18-dimethyl-9,16-dioxo-11-[[(phenylmethoxy)carbonyl]amino]-, 1,1-dimethylethyl ester, (6S,11S)- 881837-40-7 17-Oxa-2,8,15-triazanonadecanoic acid,11-amino-6-[[(1,1-dimethylethoxy)carbonyl]amino]-18,18-dimethyl-9,16-dioxo-, 1,1-dimethylethyl ester, (6S,11S)-