Mirabegron Amine(MIR-II)

Mirabegron Amine (MIR-II) is a synthetic byproduct derived from the benzimidazole core of the parent drug Mirabegron, featuring a substituted piperazine ring linked via an amine functionality. Its structure retains the 1H-benzimidazole-2-ylmethyl moiety but lacks the terminal methoxy group, replacing it with a primary amine that introduces increased basicity and hydrogen bonding potential. This impurity arises during reductive amination steps in Mirabegron synthesis, where incomplete conversion of the methoxy precursor yields the amine derivative. It serves as a critical HPLC reference standard for quantifying process-related impurities in Mirabegron active pharmaceutical ingredient batches.