4-[(2-{(1R)(2-Phenylacetylamino)[N-benzylcarbamoyl]methyl}(4S)-5,5-dimethyl(1,3-thiazolidin-4-yl))carbonylamino](3R,4R)-N-((1S)-2-hydroxy-1-phenylethyl)-3-hydroxy-5-phenylpentanamide AIDS-005491 AIDS005491 Penicillin deriv.