Mirabegron S isomer

Mirabegron S isomer is the enantiomeric impurity of (R)-Mirabegron, defined by the S-configuration at the chiral benzylic carbon within its 2-(pyridin-2-yl)ethanolamine moiety. Structurally, it features a 2-aminothiazole linked via an acetamide to a 4-(aminoethyl)phenyl core, where the terminal ethanolamine side chain exhibits the inverted absolute stereochemistry at the hydroxylated carbon compared to the parent drug. This chiral inversion affects the spatial orientation of the pyridine and hydroxyl groups relative to the core structure. It is utilized as an HPLC reference standard for controlling stereoisomeric purity in Mirabegron active pharmaceutical ingredient.