Regiospecific construction of diverse and polyfunctionalized γ-pyrone cores by indium(iii)-catalyzed annulation of diazodicarbonyls with active methylenes, 4-hydroxycoumarins, or 4-hydroxyquinolinone

An efficient and novel annulation protocol for the construction of diverse and polyfunctionalized γ-pyrones via an InBr₃-catalyzed reaction is described.