Rilpivirine Amide 1

Rilpivirine Amide 1 is a structurally related impurity derived from the parent antiretroviral drug rilpivirine, featuring a substituted pyridine core conjugated to a diarylpyrimidine scaffold with an additional amide functional group at the 5-position of the pyrimidine ring. The compound retains the characteristic 2,5-dimethylpyridine moiety but incorporates a N-(4-fluorophenyl)-N’-(2-pyridinylmethyl)urea linkage, distinguishing it through an extended hydrogen-bonding network. This impurity arises during synthetic pathways involving amidation reactions, where controlled coupling of 4-fluoroaniline with a pyridine-derived isocyanate intermediate occurs. It serves as a critical HPLC reference standard for quantifying process-related impurities in rilpivirine drug substance batches.