4-[[[3-[.beta.-[[(1,1-Dimethylethyl)amino]carbonyl]cyclohexylethylamino]-2-hydroxypropyl]amino]carbonyl]-5,5-dimethyl-.alpha.-[(phenylacetyl)amino]-N-ethyl-2-thiazolidineacetamide, [2R-[2.alpha. AIDS-006811 AIDS006811 Penicillin, cHexEtNH-OHPrNH2 analog