91Ó°ÊÓ

Electron-rich substances are used as a diene in the Diels-Alder reaction. The reactivity of dienes will be increased in the presence of an electron-releasing substituent.

Electron-poor alkenes and alkynes are the most common dienophiles.

A good dienophile has one or more electron-withdrawing groups withdrawing its density from pi-bonds.

• Find the six-membered rings with a C-C double bond.
• Draw three arrows to work in the backward direction.
• Follow the arrows to find the diene and the dienophile.

By applying the conditions, the diene and the dienophile can be identified in each case by following the mechanism.

The mechanism for the formation of (a)

So, the diene and the dienophile are as follows:

Diene and the dienophile of (a)

The mechanism for the formation of (b)

So, the diene and the dienophile are as follows:

Diene and the dienophile of (b)

The mechanism for the formation of (c)

So, the diene and the dienophile are as follows:

Diene and the dienophile of (c)