Visible Light Assisted Direct C3-H Arylation of Pyrido[1,2- a ]pyrimidin-4-ones and Thiazolo[3,2- a ]pyrimidin-5-ones.

Metal-catalyst-free, organic dye-catalyzed C3-H arylation of pyrido[1,2- a ]pyrimidin-4-ones using visible light irradiation was developed under mild reaction conditions. This operationally simple and direct C-H functionalization approach effectively produced biologically significant C3 arylated pyrido[1,2- a ]pyrimidin-4-one and thiazolo[3,2- a ]pyrimidin-5-one derivatives, including medicinally important endothelial cell dysfunction inhibitor and anti-inflammatory agents in good to excellent yields with good functional group tolerance. The present photoinduced direct C3-H arylation approach was suitable for scale-up synthesis.