Divergent Behavior of the Reactions Between 1,2-Diaza-1,3-dienes and 2,5- Dioxoimidazolidin-4-ylidene-succinates

The different base-promoted regioselective reactions between dialkyl (2E,3E)-2-[(dimethylamino)methylene]-3-(1-methyl-2,5- dioxoimidazolidin-4-ylidene)succinates and 1,2-diaza-1,3-dienes are investigated. Under the appropriate reaction conditions it is possible to turn the synthesis towards 1,3-dioxo-2,3,7,7a-tetrahydro-1H-pyrrolo[1,2-c]imidazoles or 1,3-dioxo-1,2,3,5-tetrahydroimidazo[1,5- a]pyridines. Both these transformations proceed via a double-Michael-addition.