Riociguat

Riociguat is a pyrrolo[2,3-d]pyrimidine-based compound featuring a trifluoromethyl-substituted benzene ring linked via a sulfonamide bridge to a pyrazine core. Its structure incorporates a 1H-pyrrolo[2,3-c]pyridine scaffold fused to a 1H-pyrazine-2,3-diamine moiety, with a 4-fluorophenyl group appended to the pyridine ring. The molecule exhibits a planar conjugated system stabilized by intramolecular hydrogen bonding between the sulfonamide NH and adjacent carbonyl oxygen. As the parent drug and active pharmaceutical ingredient (API), it is synthesized via a multi-step process involving palladium-catalyzed cross-coupling of fluorinated aromatic precursors. Serves as an HPLC reference standard for pharmaceutical quality control.