FP-dipicolin-methylamide Impurity (regorafenib imp-4)

FP-dipicolin-methylamide Impurity (regorafenib imp-4) is a synthetic byproduct arising from the coupling of 4-fluorophenyl and pyridine-2,6-dicarboxylic acid moieties, featuring a methylamide linkage at the pyridine-3-position. This impurity retains the core fluorophenyl-pyrazine scaffold of regorafenib but incorporates a dipicolinic acid-derived side chain with partial methylation at the amide nitrogen. Its structure includes a 4-fluorophenyl ring conjugated to a pyridine-2,6-dicarboxylic acid framework, substituted with a N-methylamide group. This compound serves as an HPLC reference standard for quantifying process-related impurities in regorafenib formulations.