Question

Predict the products of the following proposed Diels–Alder reactions.(f)

Accepted Answer

Step 1: Identify the components of the Diels–Alder reaction. The reaction involves a conjugated diene (CH3O-substituted diene) and a dienophile (cyano-substituted alkene). The diene has two double bonds in conjugation, and the dienophile has electron-withdrawing cyano groups that enhance its reactivity. Step 2: Analyze the electron flow in the reaction. The Diels–Alder reaction is a [4+2] cycloaddition, where the diene contributes four π-electrons and the dienophile contributes two π-electrons. The reaction proceeds via a concerted mechanism, forming a six-membered ring. Step 3: Determine the regiochemistry of the reaction. The electron-donating methoxy group (-OCH3) on the diene will direct the reaction due to its electronic effects. The cyano groups (-CN) on the dienophile are electron-withdrawing, influencing the orientation of the addition. The most stable product will result from the alignment of these groups to minimize steric hindrance and maximize electronic compatibility. Step 4: Predict the stereochemistry of the product. The Diels–Alder reaction is stereospecific, meaning that the stereochemistry of the diene and dienophile is preserved in the product. If the diene and dienophile are planar, the product will have cis substituents on the newly formed six-membered ring. Step 5: Draw the product structure. Combine the diene and dienophile to form a six-membered ring. The methoxy group (-OCH3) and cyano groups (-CN) will be positioned based on the regio- and stereochemical considerations discussed. Ensure the product reflects the correct connectivity and stereochemistry.

Predict the products of the following proposed Diels–Alder reactions.
(f)

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Key Concepts

Diels–Alder Reaction

Diene and Dienophile

Regioselectivity and Stereochemistry