Importance of steric effects in the [4 + 2] cycloaddition of 5-substituted pentamethylcyclopentadienes

This is the authors' abstract. We don't add key points for this paper.

Pentamethylcyclopentadienes with a carbon substituent (X = Pri, Et, CH2OH, CHO) at the C-5 position give anti cycloadducts with a variety of dienophiles, which establishes the importance of steric effects in the [4 + 2] cycloaddition of these plane-nonsymmetric dienes.