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Transition metal-free synthesis of 3-trifluoromethyl chromones via tandem C–H trifluoromethylation and chromone annulation of enaminones

The tandem C–H bond trifluoromethylation and chromone annulation reactions of o-hydroxyphenyl enaminones have been realized for the practical synthesis of 3-trifluoromethyl chromones. The reactions are performed efficiently with the promotion of K2S2O8 without using any transition metal catalyst or additive. In addition, the 3-trifluoromethyl chromone products have been successfully used for the synthesis of 3-trifluoromethyl pyrimidines by reacting with guanidine/amidine substrates.