Selective remote C–H trifluoromethylation of aminoquinolines with CF3SO2Na under visible light irradiation in the absence of an external photocatalyst

Abstract

A highly selective remote C–H trifluoromethylation of 8-aminoquinoline scaffolds in the C5-position with CF₃SO₂Na under visible light irradiation without an external photocatalyst has been developed. The protocol employs commercially available sodium trifluoromethanesulfinate (CF₃SO₂Na) as a trifluoromethylation reagent and shows a broad substrate scope, generating various 5-trifluoromethylated quinolines in good yields under photocatalyst-free, simple and mild conditions. Investigations indicated that both the starting material and product act as photosensitizers and ¹O₂ coexists with O₂˙⁻ during the reaction through energy transfer and single electron transfer processes. It is important to note that the electronic effect of the CF₃ group as a substituent introduced into quinoline rings makes their trifluoromethylation more efficient under photo-irradiation from ultraviolet to visible light in the absence of an external photocatalyst.