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

Verified step by step guidance

1. Step 1: Identify the components of the Diels–Alder reaction. The reaction involves a conjugated diene (the molecule with two double bonds, CH3-substituted diene) and a dienophile (the molecule with electron-withdrawing groups, the cyclic compound with two ketone groups).
2. Step 2: Analyze the electron flow. The Diels–Alder reaction is a [4+2] cycloaddition, where the four π-electrons from the diene interact with the two π-electrons from the dienophile to form a new six-membered ring.
3. Step 3: Determine the regiochemistry. The methyl group on the diene is an electron-donating group, which influences the orientation of the reaction. The electron-withdrawing ketone groups on the dienophile will direct the reaction to form the most stable product.
4. Step 4: Draw the product structure. Combine the diene and dienophile to form a new six-membered ring. The double bonds in the diene will disappear, and new single bonds will form between the diene and dienophile. The ketone groups will remain attached to the ring, and the methyl group will also remain attached to the ring.
5. Step 5: Consider stereochemistry. The Diels–Alder reaction is stereospecific, meaning that the stereochemistry of the diene and dienophile will influence the stereochemistry of the product. If the reaction occurs in a concerted manner, the substituents on the dienophile and diene will adopt a cis or trans relationship depending on their initial orientation.

Key Concepts

Diels–Alder Reaction

The Diels–Alder reaction is a [4+2] cycloaddition reaction between a conjugated diene and a dienophile, resulting in the formation of a six-membered ring. This reaction is a key method in organic synthesis for constructing cyclic compounds and is characterized by its stereospecificity and regioselectivity, making it a powerful tool for chemists.

Conjugated Dienes

Conjugated dienes are compounds that contain two double bonds separated by a single bond, allowing for delocalization of π electrons. This delocalization enhances the stability of the diene and increases its reactivity in Diels–Alder reactions, as it can easily interact with dienophiles to form new bonds.

Dienophile

A dienophile is a compound that contains a double or triple bond and reacts with a diene in a Diels–Alder reaction. The reactivity of a dienophile is influenced by the presence of electron-withdrawing groups, which can enhance its ability to participate in the cycloaddition, leading to the formation of more stable products.