A copper-catalyzed one-pot, three-component tandem conjugative alkynylation/6-endo cyclization sequence: access to pyrano[2,3-d]pyrimidinesElectronic supplementary information (ESI) available. See DOI: 10.1039/c5ob00380f

A copper catalyzed one-pot, three component reaction between barbituric acid, aldehydes and terminal alkynes has been developed for the construction of pyrano[2,3- d ]pyrimidines via a tandem conjugative alkynylation/6- endo cyclization pattern. Screening of barbituric acid derived organic acceptors in conjugative alkynylation reaction and the synthetic applicability of conjugative addition products under one-pot conditions were documented for the first time. A copper-catalyzed one-pot, atom/step-economical, three component method for the construction of pyrano[2,3- d ]pyrimidines has been developed via a tandem conjugative alkynylation/6- endo cyclization sequence.