Stereoselective Diels-Alder Cycloadditions
Diels-Alder cycloaddition of 5-fluorocyclopentadiene and maleic anhydride can lead to four different stereoproducts, depending on whether the fluorine is "inside" (syn) or "outside" (anti) and whether addition occurs endo or exo.
Kinetic product distributions
follow from transition state theory which assumes that each reaction
proceeds over a well defined transition state. This requires the relative
energies of transition states leading to different products together
with the temperature.
The reaction exhibits a very strong preference for syn-endo addition, in accord with observation. Anti transition states are indicated to be 25-30 kJ/mol higher in energy than the corresponding syn transition states, and exo transition states are indicated to be 15-25 kJ/mol higher in energy than the corresponding endo transition states.