(E)-(S)-4-[(S)-2-(3-{[1-(5-Methyl-isoxazol-3-yl)-methanoyl]-amino}-2-oxo-2H-pyridin-1-yl)-butanoylamino]-5-((S)-2-oxo-pyrrolidin-3-yl)-pent-2-enoic acid 2,2-dimethyl propyl ester AIDS-177218 AIDS177218