1-Imidazolidineacetic acid, 4-[(2S)-2-[[(2S)-2-[[(1,1-dimethylethoxy)carbonyl]amino]-3-methyl-1-oxobutyl]amino]-3-methyl-1-oxobutyl]-5-[[[1-[1,2-dioxo-2-(2-propenylamino)ethyl]butyl]amino]carbonyl]-2-oxo-, ethyl ester, (5R)- AIDS-222891 AIDS222891