The observation that 1, 3-cyclopentadiene is very reactive in Diels-Alder reaction, but 1, 3-cyclohexadiene is less reactive and 1, 3-cycloheptadiene is inert is to be explained. Concept introduction: In Diels-Alder reaction, a dienophile reacts with a diene to yield a cyclic adduct. The reaction takes place through 1, 4 addition of the dienophile into the diene through a cyclic transition state. These reactions occur rapidly with dienophiles having electron withdrawing substituent groups in conjugation with the double bond and if the diene adapts a s-cis conformation during the reaction. To explain: The observation that 1, 3-cyclopentadiene is very reactive in Diels-Alder reaction, but 1, 3-cyclohexadiene is less reactive and 1, 3-cycloheptadiene is inert.

Question

Reaction of HBr with 3-methylcyclohexene yields a mixture of four products: cis-and trans-1-bromo-3-methylcyclohexane and cis-and trans-1-bromo-2-methylcyclohexane. The analogous reaction of HBr with 3-bromocyclohexene yields trans-1, 2-dibromocyclohexane as the soleproduct. Draw structures of the possible intermediates, and then explain why only a single product is formed in this reaction.

Answer 1

Question

Chapter 14.SE, Problem 38AP

Interpretation Introduction

Interpretation:

The observation that 1, 3-cyclopentadiene is very reactive in Diels-Alder reaction, but 1, 3-cyclohexadiene is less reactive and 1, 3-cycloheptadiene is inert is to be explained.

Concept introduction:

In Diels-Alder reaction, a dienophile reacts with a diene to yield a cyclic adduct. The reaction takes place through 1, 4 addition of the dienophile into the diene through a cyclic transition state. These reactions occur rapidly with dienophiles having electron withdrawing substituent groups in conjugation with the double bond and if the diene adapts a s-cis conformation during the reaction.

To explain:

The observation that 1, 3-cyclopentadiene is very reactive in Diels-Alder reaction, but 1, 3-cyclohexadiene is less reactive and 1, 3-cycloheptadiene is inert.

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