The Mechanism of the Cycloaddition of Substituted Ketenes to Cyclopentadiene Based on the Bent Bond/Antiperiplanar Hypothesis Orbital Model.

The [2 + 2] cycloaddition of substituted ketenes with cyclopentadiene producing bicyclo[3.2.0]hept-2-en-6-ones is rationalized by the Bent Bond/Antiperiplanar Hypothesis (BBAH) orbital model.