The chemical properties of the α, β-unsaturated carbonyls may be explained by drawing mesomeric structures, i.e. the graphical representation of the electron delocalization effect (see Fig. ). In this approach, the molecule is assumed to be a superposition of all of its mesomeric structures. In the presented case, the susceptibility to attack of electron-rich species appears to be the result of a more positive charge present on these atoms due to the electron delocalization via the conjugated bonds, perturbed by the O orbitals, similar to what would be expected from the FOs. It is well-known that both, carbonyl and β carbon atoms are susceptible to a nucleophilic attack (see Fig. ), meaning that the atom directly bonded to the O atom and the third closest carbon atom are more positively charged. Although this is well expected for the former case due to strong polarization caused by the adjacent oxygen atom, that is not the case for the Cβ atom.