Predict the major organic product(s)of the following electrocyclic reaction.

Question

Quizplus · Accepted Answer

This is a thermal electrocyclic reaction of a cyclopentadiene molecule. The reaction undergoes an endothermic process where two pi bonds convert into two sigma bonds resulting in a three-membered ring. The stereochemistry of the product is dependent on the orientations of the pi bond ends relative to each other.

In the given reaction, only III is the correct product. The electrocyclic reaction occurs at the bond with the least thermal strain, which is the endocyclic double bond. The resulting product, cyclobutene, is in a cis configuration where the substituents on the ring occupy adjacent positions. The other two options (I and II) are not correct products since they require breaking of the exocyclic double bond carbon-carbon bond, which has significantly less thermal strain than the endocyclic bond. Hence, only option III is the major product of the given electrocyclic reaction.

Predict the Major Organic Product(s)of the Following Electrocyclic Reaction