Synthesis of benzothiazoles using fluorescein as an efficient photocatalyst under visible light

This work reports a novel and efficient method for the synthesis of benzothiazoles using 2-aminothiophenol derivatives in conjunction with aromatic aldehyde as starting materials via visible-light-induced condensation cyclization. Utilizing fluorescein as the photocatalyst and blue LED lamp as the light source, the reaction proceeds in the presence of a molecular oxygen atmosphere without the need for metal catalyst or an additional oxidant. Significantly, this method exhibits good tolerance in substrates, and a variety of 2-aminothiophenol derivatives and aromatic aldehyde are amenable to producing the corresponding benzothiazoles in high to excellent yields.