1-[{2-(3,3-Dimethyl-2-oxo-butyl)-6,6-dimethyl-4-oxo-5-[3-(1-propyl-butyl)-ureido]-heptanoylamino}-(1-ethyl-2,2-dimethyl-propylcarbamoyl)-methyl]-cyclopentanecarboxylic acid AIDS-191723 AIDS191723