Question

Draw one enantiomer of the major product of the folllowing Diels%u2013Alder reaction. (Use wedge/dash bonds to indicate the orientation of substituents in the product. Hydrogen atoms on chirality centers must be shown explicitly.) ?

Answer 1

Concepts and reason

Diels–Alder Reactions:

Diels–Alder reaction is a [4 + 2] cycloaddition reaction between a conjugated diene and a dienophile (substituted alkene or alkyne) to form a substituted cyclohexene. This reaction occurs in a single step with no intermediates.

Chiral Centers or Chirality Centers:

A chiral center is a carbon atom in an organic molecule that is directly attached by four different substituents causing for optical isomerism.

Fundamentals

Diels–Alder Reaction:

Reactions of dienes with di- substituted dienophiles:

Regioselectivity of Diels–Alder Reaction:

Ans:

The major cycloaddition product is shown below:

Answer 2

Consider the resonance structures of the diene and the dienophile:

On the diene resonance on the left, you have a negative charge on the terminal, and on the dienophile on the right you have positive charge on the carbon at the bottom. As they say opposites attract, so one enantiomer of the product will be the endo product in which you have to flip the dienophile first so that the aldehyde is at the bottom and the deuterium is at the top:

Answer 3