7-​Amino-​4-​hydroxy-​3-​[2-​(4-​methoxyphenyl)​diazenyl]​-​2-​naphthalenesulfonic Acid 1-​Methylethyl Ester is an intermediate in synthesizing 7-[[4-[Bis(3-Amino-3-oxopropyl)amino]-6-chloro-1,3,5-triazin-2-yl]amino]-4-hydroxy-3-[(4-methoxyphenyl)azo]-2-naphthalenesulfonic Acid (B426265), which acts as a non-peptide hormone receptor antagonist affecting physiological homeostasis and reproduction. Hormone antagonist.