4-({[((2R,4S)-2-{(1R)-2-(benzylamino)-2-oxo-1-[(phenylacetyl)amino]ethyl}-5,5-dimethyl-1,3-thiazolidin-4-yl)carbonyl]amino}methyl)-N-(tert-butyl)-4-hydroxy-1-isobutyl-L-prolinamide AIDS-060991 AIDS060991 Proline analog Thiazolidine analog