Visible light-induced g-C3N4 Catalyzed C-H acylation and trifluoromethylation of quinoxalinones: an efficient and recyclable approach

Photoinduced C-H functionalization of quinoxalines is a key transformation for the derivatization of biologically relevant molecules. Traditionally, homogeneous catalysts such as transition metal complexes or organic dyes are indispensable for these transformations. However, these methods often suffer from limitations related to cost, recyclability, and environmental impact. Herein, by using inexpensive, readily available and recyclable graphitic carbon nitride (g-C3N4) as a heterogeneous photocatalyst, a diverse range of acyl- and trifluoromethyl-functionalized quinoxalinone derivatives were synthesized in good to excellent yields under the irradiation of blue LEDs. Control experiments confirmed that the photogenerated electrons played a pivotal role in promoting the generation of acyl and trifluoromethyl radical intermediates. Moreover, g-C3N4 showed no significant loss of activity after at least six reaction cycles. Potentially, g-C3N4 represents a promising alternative to noble metal photocatalysts in organic synthesis.