Emtricitabine Impurity 18

Chemical Name: ((((R)-1-(6-((((5-fluoro-1-((2R,5S)-2-(hydroxymethyl)-1,3-oxathiolan-5-yl)-2-oxo-1,2-dihydropyrimidin-4-yl)amino)methyl)amino)-9H-purin-9-yl)propan-2-yl)oxy)methyl)phosphonic acid