Discovery of thienoimidazole-based HCV NS5A inhibitors. Part 2: non-symmetric inhibitors with potent activity against genotype 1a and 1b.

The discovery of non-symmetric thienoimidazole-containing HCV NS5A inhibitors is described. The inhibitors herein reported display high potencies against both genotype 1a and 1b. In this follow-up manuscript, we discuss the importance of the linker aromaticity to achieve high potency, particularly against genotype 1a.

Synthesis and evaluation of NS5A inhibitors containing diverse heteroaromatic cores.

Inhibitors of the HCV NS5A nonstructural protein are showing promising clinical potential in the treatment of hepatitis C when used in combination with other direct-acting antiviral agents. Current NS5A clinical candidates such as daclatasvir, ledipasvir, and ombitasvir share a common pharmacophore that features a pair of (S)-methoxycarbonylvaline capped pyrrolidines linked to various cores by amides, imidazoles and/or benzimidazoles. In this Letter, we describe the evaluation of NS5A inhibitors which contain alternative heteroaromatic replacements for these amide mimetics. The SAR knowledge gleaned in the optimization of scaffolds containing benzoxazoles was parlayed toward the identification of potent NS5A inhibitors containing other heteroaromatic replacements such as indoles and imidazopyridines.

Discovery of thienoimidazole-based HCV NS5A inhibitors. Part 1: C2-symmetric inhibitors with diyne and biphenyl linkers.

The discovery of C2-symmetric bis-thienoimidazoles HCV NS5A inhibitors is herein reported. Two straightforward approaches to access the requisite diyne and biphenyl linker moieties are described. This study revealed the paramount importance of the aromatic character of the linker to achieve high genotype 1a potency.

Benzimidazole-containing HCV NS5A inhibitors: effect of 4-substituted pyrrolidines in balancing genotype 1a and 1b potency.

The treatment of HCV with highly efficacious, well-tolerated, interferon-free regimens is a compelling clinical goal. Trials employing combinations of direct-acting antivirals that include NS5A inhibitors have shown significant promise in meeting this challenge. Herein, we describe our efforts to identify inhibitors of NS5A and report on the discovery of benzimidazole-containing analogs with subnanomolar potency against genotype 1a and 1b replicons. Our SAR exploration of 4-substituted pyrrolidines revealed that the subtle inclusion of a 4-methyl group could profoundly increase genotype 1a potency in multiple scaffold classes.