Abstract 6-[(Dimethylamino) methylene] amino-1, 3-dimethyluracil 1 undergoes formal [4+ 2] cycloaddition reactions with electron deficient olefins to give pyrido [2, 3-d] pyrimidines. With DMAD or azodicarboxylates Michael addition occurs leading to pyrrolo [3, 4-c] pyridines (X- ray analysis) and theophylline derivatives.
![methyl 1,3-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidine-6-carboxylate Structure](https://image.chemsrc.com/caspic/037/120788-68-3.png)