Synthesis of dipeptide-type human immunodeficiency virus (HIV) protease inhibitors with a binding unit to gp120

Some dipeptide-type human immunodeficiency virus (HIV) protease inhibitors derived from KNI-102, with a N-carbomethoxycarbonylprolyl-phenylalanine benzyl ester (CPF) moiety as a binding site to gp120, were synthesized. Compounds 11a showed 7--100 times higher HIV protease-inhibitory activity (11a; IC50 = 0.90 microgram/ml, 1.1 microM) than the standard compound 3 or 4 (3; IC50 = 3.7 micrograms/ml, 7.7 microM, 4; IC50 = 75 micrograms/ml, 155 microM). Generally, the compounds substituted at the o-position of the phenoxyacetyl group 7a, 11a, 16a and 21a showed several times higher inhibitory activity than 3.