ethyl (2E,4S)-4-[((2R)-2-{[N-(tert-butoxycarbonyl)-L-valyl]amino}-2-phenylethanoyl)amino]-5-[(3S)-2-oxopyrrolidin-3-yl]pent-2-enoate
ethyl (2e,4s)-4-[((2r)-2-{[n-(tert-butoxycarbonyl)-l-valyl]amino}-2-phenylethanoyl)amino]-5-[(3s)-2-oxopyrrolidin-3-yl]pent-2-enoate