Visible-light-driven three-component annulation for the synthesis of highly functionalized 2-iminothiazolidin-4-ones without photocatalysts.

We have developed a photocatalyst/base/metal-free, visible-light-driven three-component annulation protocol to access fully substituted 2-iminothiazolidin-4-one derivatives from isothiocyanates, amines, and aryl diazoacetates using a low-energy white light source at room temperature in open air. The [2 + 2 + 1] reaction undergoes successive C–N/C–S bond formation in one pot. This transformation proceeds under extremely mild conditions with a good yield and a good functional group tolerance. Mechanistic studies showed that the reaction involves the formation of free carbene intermediates from aryl diazoacetates under visible light irradiation. [ABSTRACT FROM AUTHOR]