Visible-light-mediated one-pot efficient synthesis of 1-aryl-1H,3H-thiazolo[3,4-a]benzimidazoles: a metal-free photochemical approach in aqueous ethanol

A new metal-free approach to construct medicinally valuable 1-aryl-1 H ,3 H -thiazolo[3,4- a ]benzimidazoles under visible light irradiation in aqueous ethanol medium at room temperature has been developed. The present process was performed with 1,2-phenylenediamines, aromatic aldehydes and 2-mercaptoacetic acid utilizing a simple household 22 W compact fluorescent lamp to generate C–S, C–N bonds through radical intermediates. This visible-light-promoted synthesis provides lower cost, operation simplicity and high functional groups tolerating ability with short reaction time and high yield under mild reaction conditions. Graphic abstract