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

Question

Quizplus · Accepted Answer

The electrocyclic reaction shown is a thermal [4+2] cycloaddition between a conjugated diene and a dienophile. The reaction proceeds through a concerted mechanism to form a six-membered ring.

Only products I and II can be formed because they both involve the thermal [4+2] cycloaddition of the conjugated diene and dienophile shown. III cannot be formed because it involves a different diene and dienophile combination that is not present in the reactants.

Product I is formed by closing the cyclohexene ring with the double bonds on carbons 1 and 4, while product II is formed by closing the ring with the double bonds on carbons 2 and 5. These two products are constitutional isomers and cannot be interconverted without breaking covalent bonds. Therefore, the correct answer is D.

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