AIDS-005471 AIDS005471 Penicillin deriv. [2R-[2.alpha.(R*),4.beta.(S)]]-5,5-Dimethyl-.alpha.-[(phenylacetyl)amino]-N-(phenylmethyl)-4-[[[-3-phenyl-1-(hydroxymethyl)propyl]amino]carbonyl]-2-thiazolidineacetamide