Novel HCV NS5B polymerase inhibitors derived from 4-(1',1'-dioxo-1',4'-dihydro-1'lambda6-benzo[1',2',4']thiadiazin-3'-yl)-5-hydroxy-2H-pyridazin-3-ones. Part 1: exploration of 7'-substitution of benzothiadiazine.

5-Hydroxy-3(2H)-pyridazinone derivatives were investigated as inhibitors of genotype 1 HCV NS5B polymerase. The synthesis, structure-activity relationships (SAR), metabolic stability, and structure-based design approach for this new class of compounds are discussed.