The influenza RNA polymerase complex, which consists of the three subunits PA, PB1, and PB2, is a promising target for the development of new antiviral drugs. A large library of benzofurazan compounds was synthesized and assayed against influenza virus A/WSN/33 (H1N1). Most of the new derivatives were found to act by inhibiting the viral RNA polymerase complex through disruption of the complex formed between subunits PA and PB1. Docking studies were also performed to elucidate the binding mode of benzofurazans within the PB1 binding site in PA and to identify amino acids involved in their mechanism of action. The predicted binding pose is fully consistent with the biological data and lays the foundation for the rational development of more effective PA–PB1 inhibitors.

In the fight against influenza virus A/WSN/33 (H1N1), the PA–PB1 protein–protein interaction is emerging as a new drug target. To identify small molecules able to inhibit the viral RNA polymerase complex, the benzofurazan scaffold was explored by synthesizing a large library of derivatives. Some compounds showed high anti‐H1N1 activity and emerged as effective inhibitors of the PA–PB1 interaction, with IC50 values in the micromolar range.