A green and transition-metal-free light-mediated trifluoromethylation reaction of coumarins

An efficient and practical approach to the photoinduced trifluoromethylation of coumarins in the absence of additional metal photocatalyst was developed with easily handled CF3SO2Na. Significantly, this photochemical strategy employed acetone, one of the most widely used and cheapest organic solvents, instead of expensive metal catalyst or dangerous peroxides to generate CF3 radical, which provides a green route to cost-effective large-scale synthesis of trifluoromethylated chemicals.