3- nitro Apremilast

3-nitro Apremilast is a structurally related impurity derived from the parent drug Apremilast, featuring a nitro group substitution at the C3 position of the pyridone ring. This modification introduces an electron-withdrawing nitro moiety, altering the compound's electronic distribution and reactivity compared to the parent molecule. The core structure retains the cyclohexane-1,3-dione scaffold and pyridine-2,5-dione pharmacophore, with the nitro group positioned ortho to the key amide linkage. This impurity arises during synthetic pathways due to competitive nitration reactions. It serves as a critical HPLC reference standard for quantifying process-related impurities in Apremilast formulations.