Chapter 27, Problem 27.45P

Interpretation Introduction

(a)

Interpretation: The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is to be drawn.

Concept introduction: In the sigmatropic rearrangement, the rearrangement of pi bond and the breaking of sigma bond take place. This results in the generation of new sigma bond in the product. In this type of rearrangement, the number of pi bonds remains constant in the reactant as well as in the product.

Curved arrows aid in determining the movement and flow of electrons in the reaction. The electrons that take part in the chemical reactions are shown by the curved arrows.

Answer to Problem 27.45P

The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is,

Explanation of Solution

The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is shown below.

[a1]

Figure 1

The above diagram indicates that in the product, both the $\text{π}$ bonds are rearranged. The old $\text{σ}$ bond breaks at third carbon atom and simultaneously a new $\text{σ}$ bond is formed at sixth carbon atom during the conversion of starting material into the product. Therefore, the product is formed with $\left[3,3\right]$ sigmatropic rearrangement.

Thus, the name of product is $1-\left(3-\text{methylcyclohex}-3-\text{enyl}\right)\text{ethanone}$.

Conclusion

The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is $1-\left(3-\text{methylcyclohex}-3-\text{enyl}\right)\text{ethanone}$.

Interpretation Introduction

(b)

Interpretation: The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is to be drawn.

Concept introduction: In the sigmatropic rearrangement, the rearrangement of pi bond and the breaking of sigma bond take place. This results in the generation of new sigma bond in the product. In this type of rearrangement, the number of pi bonds remains constant in the reactant as well as in the product.

Curved arrows aid in determining the movement and flow of electrons in the reaction. The electrons that take part in the chemical reactions are shown by the curved arrows.

Answer to Problem 27.45P

The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is,

Explanation of Solution

The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is shown below.

Figure 2

The above diagram indicates that in the product, both the $\text{π}$ bonds are rearranged. The old $\text{σ}$ bond breaks at third carbon atom and simultaneously a new $\text{σ}$ bond is formed at sixth carbon atom during the conversion of starting material into the product. Therefore, the product is formed with $\left[3,3\right]$ sigmatropic rearrangement.

Thus, the name of product is $2,5,8-\text{trimethylcyclonona}-1,5-\text{dienol}$.

Conclusion

The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is $2,5,8-\text{trimethylcyclonona}-1,5-\text{dienol}$.

Interpretation Introduction

(c)

Interpretation: The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is to be drawn.

Concept introduction: In the sigmatropic rearrangement, the rearrangement of pi bond and the breaking of sigma bond take place. This results in the generation of new sigma bond in the product. In this type of rearrangement, the number of pi bonds remains constant in the reactant as well as in the product.

Curved arrows aid in determining the movement and flow of electrons in the reaction. The electrons that take part in the chemical reactions are shown by the curved arrows.

Answer to Problem 27.45P

The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is,

Explanation of Solution

The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is shown below.

Figure 3

The above diagram indicates that in the product, both the $\text{π}$ bonds are rearranged. The old $\text{σ}$ bond breaks at third carbon atom and simultaneously a new $\text{σ}$ bond is formed at sixth carbon atom during the conversion of starting material into the product. Therefore, the product is formed with $\left[3,3\right]$ sigmatropic rearrangement.

Thus, the name of product is $\text{6-methyl-1, 2, 4a, 5, 8, 8a-hexahydronaphthalene}$.

Conclusion

The product of the $\left[3,3\right]$ sigmatropic rearrangement for the given compound is $\text{6-methyl-1, 2, 4a, 5, 8, 8a-hexahydronaphthalene}$.