AIDS-033406 AIDS033406 Dimethyl (2R,2'R)-2,2'-(hydrazine-1,2-diylbis{carbonyl[(2R,4S)-5,5-dimethyl-1,3-thiazolidine-4,2-diyl]})bis{[(phenylacetyl)amino]acetate} Penicillin N2 sym dimer