The explanation for the fact that the modes, [ 4 a + 2 s ] and [ 4 s + 2 a ] of cycloaddition are not allowed is to be stated with the help of a frontier orbital analysis. Concept introduction: Diels Alder reaction is the [ 4 + 2 ] cycloaddition reaction between a conjugated diene and a dienophile to give a cycloaddition product. It is an electrocyclic reaction in which the 4 π and 2π electrons of a diene and dienophile are involved respectively. The product is formed by the [ 1 , 4 ] addition, that is, the carbons of the dienophile are attached to the first and fourth carbon of the diene.

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Chapter 28, Problem 28.11P

Interpretation Introduction

Interpretation:

The explanation for the fact that the modes, [4a + 2s] and [4s + 2a] of cycloaddition are not allowed is to be stated with the help of a frontier orbital analysis.

Concept introduction:

Diels Alder reaction is the [4+2] cycloaddition reaction between a conjugated diene and a dienophile to give a cycloaddition product. It is an electrocyclic reaction in which the 4π and 2π electrons of a diene and dienophile are involved respectively. The product is formed by the [1,4] addition, that is, the carbons of the dienophile are attached to the first and fourth carbon of the diene.

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