Push-pull ethylenes geometries

Pappalardo, R. R., Sanchez Marcos, E., Ruiz-Lopez, M. F., Rinaldi, D. and Rivail, J. L. Solvent effects on molecular geometries and isomerization processes A study of push-pull ethylenes in solution, JAm.Chem.Soc., 115 (1993), 3722-3730... 

In the ground state, aminomethylenemalonates possess an essentially planar geometry, which maximizes the electron delocalization in the molecules. In the heteropolar transition state, the plane of the groups R3 and NR R2 and the plane of the two carbonyl groups occupy orthogonal positions. More details of the dynamic and static stereochemistry of push-pull ethylenes, as in compounds 1 and 2, are discussed in two excellent reviews (73TS295 83TS83). 

R. R. Pappalardo, E. S. Marcos, M. F. Ruiz-Lopez, D. Rinaldi, and J.-L. Rivail, /. Am. Chem. Soc., 115, 3722 (1993). Solvent Effects on Molecular Geometries and Isomerization Processes A Study of Push-Pull Ethylenes in Solution. 

---