A copper-catalyzed one-pot, three-component tandem conjugative alkynylation/6-endo cyclization sequence: access to pyrano[2,3-d]-pyrimidines.

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.