The synthesis of free compound is performed as follows: The condensation of 2-hydroxy-4-(3-methyl-2-butenyloxy)acetophenone (I) with 4-tert-butylbenzaldehyde (II) by means of KOH in hot ethanol gives 3-(4-tert-butylphenyl)-1-[4-hydroxy-4-(3-methyl-2-butenyloxy)phenyl]-2(E)-propen-1-one (III), which is condensed with ethyl bromoacetate (IV) by means of KOH in acetone to afford (E)-2-[2-(4-tert-butylcinnamoyl)-4-(3-methyl-2-butenyloxy)phenoxy] acetic acid ethyl ester (V). Finally, this compound is hydrolyzed with KOH in hot ethanol-water.