4-[N-(1-{N-[1-(N-{(1R)-1-[N-({[(5S,1R)-8-Ethyl-6-(methylsulfonyl)-7-oxo-2,6-diazabicyclo[3.3.0]oct-2-yl]oxycarbonyl}methyl)carbamoyl]-2-methylpropyl}carbamoyl)(1S)-2-methylpropyl]carbamoyl}(1S)-2-carboxyethyl)carbamoyl](4S)-4-(acetylamino)butanoic acid AIDS-154665 AIDS154665