Pyrimidines. 54. Ring Transformation of 5-(2-Carbamoylvinyl)uracil Derivatives to 5-Carbamoylpyridin-2-ones

Article abstract of DOI:10.1021/jo00209a030

Reaction of 5-formyluracil derivatives 1 with (carbamoylmethylene)triphenylphosphorane led to the formation of both the corresponding (Z)- and (E)-5-(2-carbamoylvinyl)uracil derivatives 2 and 3.Upon treatment of the Z isomers 2 with ethanolic sodium ethoxide, a mononuclear heterocyclic rearrangement occurred easily to give 3-(ethoxycarbamoyl)pyridin-6-ones (4) and 3-(N-substituted carbamoyl)pyridin-6-ones (5).Under the analogous conditions, the E isomers 3 were converted into 4 and 5 together with 3-(N-substituted carbamoyl)-1-methylpyridin-6-ones (6).Addition of water to the reaction mixture accelerated the conversion of 3 into 6.Conceivable reaction sequences for the present pyrimidine-to-pyridine transformations are discussed.