Iron(III)-Catalyzed Peroxide-Mediated C-3 Functionalization of Flavones

An iron(III)-catalyzed C-3 functionalization of flavones has been achieved using tert-butyl peroxybenzoate (TBPB)/potassium persulphate (K2S2O8) oxidant combinations with a suitable solvent. In the presence of iron(III)/tert-butyl peroxybenzoate/potassium persulphate, the reaction of flavones in cycloalkanes afforded exclusive C-3 cycloalkylation via C-sp2-C-sp3 coupling, whereas the solvent N,N-dialkylformamide provided C-3 amidation via C-sp2-C-sp2 coupling. Under identical reaction conditions just by switching the solvent to chlorobenzene, C-3 methylated flavones were obtained where tert-butyl peroxybenzoate (TBPB) served as the source of the methyl group.