Diels-Alder Reaction: Transition State Structure of E-1,3-pentadiene

The transition state structure for the interconversion of s-cis and s-trans E-1,3-pentadiene. This structure is about 6.1 kcal/mol less stable than the s-trans conformation. Hence the conversion between the s-trans and s-cis conformational isomers is fast and occurs even at very low temperature.

Figure. The MP2(full)/6-31G* optimized structure of the transition state structure for the conformational interconversion between s-trans and s-cis E-1,3-pentadiene.