We describe the structure–activity relationship of the C7-position of pyrano[3,4-b]indole-based inhibitors of HCV NS5B polymerase. Further exploration of the allosteric binding site led to the discovery of the significantly more potent compounds 13 and 14. ... We describe the structure–activity relationship of the C7-position of pyrano[3,4-b]indole-based inhibitors of HCV NS5B polymerase. Further exploration of the allosteric binding site led to the discovery of ...