A fulgide, 3,4-bis[1-(2,5-dimethyl-3-thienyl)ethylidene]-3,4-dihydro-2,5-furandione, was synthesized by Pd-catalyzed carbonylation of the corresponding 2-butyne-1,4-diol derivative. UV-irradiation to the ZZ-form in toluene resulted in the formation of two diastereomeric colored forms by way of EE-and EZ-forms. The colored form from the EE-form was predominant in 90% de.