AIDS-005321 AIDS005321 Cyclohexanehexamide, .delta.-(acetylamino)-.gamma.-hydroxy-.alpha.-(1-methylethyl)-N-(D)-[2-methyl-1-[[(2-pyridinylmethyl)amino]carbonyl]butyl] U-81749E analog psi-[CHOHCH2] cHexAla Val-Ile isostere