AIDS-005391 AIDS005391 Penicillin Et(NH)2 dimer [2R-[2.alpha.(R*),4.-beta.-]]-4,4'-[1,2-Ethanediylbis[aminocarbonyl]]bis[5,5-dimethyl-.alpha.-3-methylbutyramido-2-thiazolidineacetic acid, methyl ester]