Design and Synthesis of P2–P4 Macrocycles Containing a Unique Spirocyclic Proline: A New Class of HCV NS3/4A Inhibitors

A new class of hepatitis C NS3/4A inhibitors was identified by introducing a novel spirocyclic proline–P2 surrogate onto the P2–P4 macrocyclic core of MK-5172 (grazoprevir). The potency profile of new analogues showed excellent pan-genotypic activity for most compounds. The potency evaluation included the most difficult genotype 3a (EC50 values ≤10 nM) and other key genotype 1b mutants. Molecular modeling was used to design new target compounds and rationalize our results. A synthetic approach based on the Julia–Kocienski olefination and macrolactamization to assemble the P2–P4 macrocyclic core containing the novel spirocyclic proline–P2 moiety is presented as well.