An effective tandem reaction of 4-aminocoumarins and 1,3-diarylpropenes mediated by Cu(OTf)2/TBHP (tert-butyl hydroperoxide)/O2 that provides various benzopyrano[4,3-b]pyridines in moderate to good yields is disclosed. The reaction proceeds through oxidative coupling, intramolecular cyclization, and dehydro-aromatization. This approach has the advantages of high atom-economy, environmental compatibility, and wide substrate scope.
Key words
tandem reaction - oxidative coupling - TBHP - 4-aminocoumarin - benzopyrano[4,3-
b]pyridines