Fosaprepitant (S, S, S)Dimeglumine

Fosaprepitant (S,S,S)Dimeglumine is a distinct stereoisomeric impurity of the phosphoramidate prodrug Fosaprepitant, existing as its dimeglumine salt. This compound retains the core phosphoramidate linkage and morpholine ring system characteristic of the parent API but differs in the absolute configuration at each of its three chiral centers. Specifically, it presents an altered stereochemistry at the benzylic ether, the morpholine-substituted carbon, and the primary carbon adjacent to the phosphoramidate nitrogen, compared to the pharmacologically active form. Its structure features multiple trifluoromethyl substituents, a key fluorinated aryl moiety, and a carbamate group, all integral to the fosaprepitant scaffold. This specific stereoisomer is essential as a chromatographic reference standard for the chiral purity assessment and impurity profiling of Fosaprepitant API.