Pyrrolidine-5,5-trans-lactams. 4. Incorporation of a P3/P4 Urea Leads to Potent Intracellular Inhibitors of Hepatitis C Virus NS3/4A Protease

Abstract
In this, the first of two Letters, we describe how a P3/P4 urea linking unit was used to greatly enhance the biochemical and replicon potency of inhibitors based upon the pyrrolidine-5,5-trans-lactam template. Compound 7b demonstrated a 100 nM IC50 in the replicon cell-based surrogate HCV assay.