4-[[[3-[.beta.-[[(1,1-Dimethylethyl)amino]carbonyl]-N-methyl-cyclohexylethylamino]-2-hydroxypropyl]amino]carbonyl]-5,5-dimethyl-.alpha.-[(phenylacetyl)amino]-N-ethyl-2-thiazolidineacetamide, [2R-[2. AIDS-006812 AIDS006812 Penicillin, cHexEtNH-OHPrNH2 analog