This compound has been obtained by several related ways: 1. The condensation of 3,5-di-tert-butyl-4-hydroxybenzaldehyde (I) with rhodanine (II) by means of NaOAc in refluxing HOAc gives 5-(3,5-di-tert-butyl-4-hydroxybenzylidene)-2-thioxothiazolidin-4-one (III), which is reduced with H2 over Pd/C in hot ethanol to yield the target compound along with its benzylidene analogue; these are separated by chromatography. 2. The 5-(3,5-di-tert-butyl-4-hydroxybenzylidene)-2-thioxothiazolidin-4-one (III) is reduced with 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylic acid diethyl ester (IV) in hot toluene to give 5-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-thioxothiazolidin-4-one (V), which is desulfurized to the target compound with H2 over 5% Pd/C (3) or with a great excess of Zn in acetic acid. 3. The reaction of 5-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-thioxothiazolidin-4-one (V) with ammonia and formaldehyde in methanol also gives the target compound through the nonisolated intermediate (VI).