AIDS-033404 AIDS033404 Methyl (2R)-{(2R,4S)-4-[({2-[({(5R,6R)-3,3-dimethyl-7-oxo-6-[(phenylacetyl)amino]-4-thia-1-azabicyclo[3.2.0]hept-2-yl}carbonyl)amino]ethyl}amino)carbonyl]-5,5-dimethyl-1,3-thiazolidin-2-yl}[(phenylacetyl)amino]acetate Penicillin Et(NH)2 dimer