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.

Open "Diels-Alder 5-fluorocyclopentadiene+maleic anhydride". All four transition states will be displayed, together with a spreadsheet providing energies relative to the "syn-endo" transition state. You can go between the different transition states by clicking on each.



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.