AFP-PmA ethylcarbamate Impurity

AFP-PmA ethylcarbamate Impurity is a structurally related byproduct derived from the amidation cascade in Regorafenib synthesis. It features a substituted pyrimidine core fused to a benzimidazole ring system, with an ethylcarbamate moiety appended to the 2-amino pyrimidine position. The fluorophenyl substituent on the pyrimidine ring retains the parent drug's aromatic heterocyclic architecture. This impurity arises via nucleophilic attack of ethyl isocyanate on an intermediate amidine, forming a stable carbamate linkage. It serves as a critical HPLC reference standard for quantifying process-derived impurities in Regorafenib active pharmaceutical ingredient batches.