Diels Alder Reaction

Diels Alder Reaction

Contents

• Cycloaddition reaction

• Diel’s Alder reaction

Learning Objectives

At the end of this lecture, student will be able to

• Explain the concept involved in Diel’s Alder reaction

• Explain Cyclo addition reaction

Carbenes

• Definition

– Carbon with lone pair of electrons

– Highly reactive

• Examples

– Methylene, dichloro carbene

• Generation

Cycloaddition Reaction

• Addition of carbene to alkene - cycloaddition

Types of cycloaddition reactions

• [2+2] cycloaddition

• [4+2] cycloaddition

[2+2] cycloaddition

• Example

[4+2] cycloaddition or Diels - Alder reaction

– 1,4 - addition reaction

– Conjugated diene and dienophile

• Example

• Mechanism

• Reactivity of dienophile increased with electron withdrawing group

• Examples

Summary

• Carbenes – divalent carbon compounds – highly unstable

• Cycloaddition reactions – carbenes add to alkenes to generate cyclic ring

• Types of cycloaddition reactions - [4+2] cycloaddition and [2+2] cycloaddition

• Diel’s Alder reaction - [4+2] cycloaddition reaction – involves reaction between conjugated dienes and dienophile