Elagolix Dialkylated Impurity ; Elegolix Diacid Impurity ; (R)-4,4'-((2-(5-(2-Fluoro-3-methoxyphenyl)-3-(2-fluoro-6-(trifluoromethyl)benzyl)-4-methyl-2,6-dioxo-3,6-dihydropyrimidin-1(2H)-yl)-1-phenylethyl)azanediyl)dibutyric acid;