The synthesis and transformations of methyl 2-[2,2-bis(ethoxycarbonyl)ethenyl]amino-3-dimethylaminobut-2-enoate. The synthesis of 3-amino-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-ones

Methyl 2-[2,2-bis(ethoxycarbonyl)ethenyl]amino-3-dimethylaminobut-2-enoate (3) was prepared from methyl N-2,2-bis(ethoxycarbonyl)vinylglycinate (2) and DMADMA, and used as a reagent for the preparation of substituted 3-amino-2-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidines (13-17), 4H-benzothiazolo[3,2-a]pyrimidin-4-one (18), 5H-thiazolo[3,2-a]pyrimidin-5-one (19), and 4-methyl-tetrahydro-2H-1-benzopyran-2-ones (20) and (21).