ferb 033 ferb 033 ferb 033 is a synthetic, nonsteroidal estrogen that was synthesized in 2009 and is used in scientific research. it is a potent and selective erβ agonist (ki = 7.1 nm, ec50 = 4.8 nm), with 62-fold selectivity for the erβ over the erα. ferb 033identifiers iupac name 2-chloro-3′-fluoro-3,4′-dihydroxy--4-carboxaldehyde oxime cas number1111084-78-6 ychemspider24606020unii9fut9fh3exchemical and physical dataformulac13h9clfno3molar mass281.67 g·mol−13d model (jsmol)interactive image smiles c1cc(c(cc1c2ccc(c(c2cl)o)/c=n/o)f)o inchi inchi=1s/c13h9clfno3/c14-12-9(3-1-8(6-16-19)13(12)18)7-2-4-11(17)10(15)5-7/h1-6,17-19h/b16-6+key:lrrmqngsyouany-omciszlksa-n