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

Abstract

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.