Visible-Light-Promoted Three-Component Coupling Annulation: Synthesis of 2-Iminothiazolidin-4-ones via in Situ Formed Electron Donor-Acceptor Complexes.

A novel and efficient three-component coupling annulation strategy for the synthesis of 2-iminothiazolidin-4-ones from amines, isothiocyanates, and alkyl acetylenedicarboxylates under visible-light irradiation conditions has been demonstrated. In this transformation, the in situ formed photoactive electron donor-acceptor (EDA) complexes facilitate the reaction and smoothly generate the corresponding products with a high adaptability under mild conditions. This protocol provides a cost-efficient and practical route to 2-iminothiazolidin-4-ones and promotes potential applications on the synthetic drugs.