The condensation of 3,5-bis(tert-butyl)-4-hydroxybenzaldehyde (I) with 2-iminothiazolidin-4-one (II) in refluxing acetic acid gives darbufelone (III), which is then treated with methanesulfonic acid in THF.
Knoevenagel condensation of benzaldehyde (I) with rhodanine (II) by means of sodium acetate in acetic acid afforded benzylidenethione (III). Alkylation with iodomethane in the presence of triethylamine gave methylthioether (IV), which was finally condensed with methoxamine hydrochloride and potassium tert--butoxide in refluxing ethanol to yield the title compound.