Chapter 21, Problem 21.67P

Interpretation Introduction

(a)

Interpretation:

The synthesis of given compound using a Claisen condensation is to be shown.

Concept introduction:

In Claisen condensation, ethyl ethanoate (ethyl acetate) is treated with sodium ethoxide, followed by acid work up, a $\text{β-keto }$ ester is produced. A successful Claisen condensation generally requires at least two $\text{α}$ protons on the initial ester. The first $\text{α}$ proton required to produce the enolate anion and second $\text{α}$ proton favor overall product and significant amount of $\text{β-keto }$ ester isolated. The Claisen condensation has the potential for an intramolecular reaction, ultimately producing a ring which is called a Dieckmann condensation. An intramolecular nucleophilic addition-elimination reaction on an ester occur if the enolate anion derives from the portion of a molecule characteristic of a ketone or aldehyde.

Answer to Problem 21.67P

The synthesis of given compound is shown below.

Explanation of Solution

The given compound is,

The disconnection of $\text{C-C}$ bond at the $\text{α}$ and $\text{β}$ carbon of the given compound and by reattaching an alkoxy leaving group yields two identical ester precursors. The base required is ${\left({\text{CH}}_{\text{3}}\right)}_{\text{2}}{\text{CHO}}^{\text{-}}$.

The Claisen reaction in the forward direction would proceed as follows:

Conclusion

The Claisen and Dieckmann condensations are new $\text{C-C}$ bond forming reactions proceed under basic condition.

Interpretation Introduction

(b)

Interpretation:

The synthesis of given compound using a Claisen condensation is to be shown.

Concept introduction:

In Claisen condensation, ethyl ethanoate (ethyl acetate) is treated with sodium ethoxide, followed by acid work up, a $\text{β-keto }$ ester is produced. A successful Claisen condensation generally requires at least two $\text{α}$ protons on the initial ester. The first $\text{α}$ proton required to produce the enolate anion and second $\text{α}$ proton favor overall product and significant amount of $\text{β-keto }$ ester isolated. The Claisen condensation has the potential for an intramolecular reaction, ultimately producing a ring which is called a Dieckmann condensation. An intramolecular nucleophilic addition-elimination reaction on an ester occur if the enolate anion derives from the portion of a molecule characteristic of a ketone or aldehyde.

Answer to Problem 21.67P

The synthesis of given compound is shown below.

Explanation of Solution

The given compound is,

The disconnection of $\text{C-C}$ bond at the $\text{α}$ and $\text{β}$ carbon of the given compound and by reattaching an alkoxy leaving group yield a molecule with two ester groups. The base required is ${\text{CH}}_{\text{3}}{\text{O}}^{\text{-}}$.

The Dieckmann reaction in the forward direction would proceed as follows:

Conclusion

The Claisen and Dieckmann condensations are new $\text{C-C}$ bond forming reactions proceed under basic condition.

Interpretation Introduction

(c)

Interpretation:

The synthesis of given compound using a Claisen condensation is to be shown.

Concept introduction:

In Claisen condensation, ethyl ethanoate (ethyl acetate) is treated with sodium ethoxide, followed by acid work up, a $\text{β-keto }$ ester is produced. A successful Claisen condensation generally requires at least two $\text{α}$ protons on the initial ester. The first $\text{α}$ proton required to produce the enolate anion and second $\text{α}$ proton favor overall product and significant amount of $\text{β-keto }$ ester isolated. The Claisen condensation has the potential for an intramolecular reaction, ultimately producing a ring which is called a Dieckmann condensation. An intramolecular nucleophilic addition-elimination reaction on an ester occur if the enolate anion derives from the portion of a molecule characteristic of a ketone or aldehyde.

Answer to Problem 21.67P

The synthesis of given compound is shown below.

Explanation of Solution

The given compound is,

The disconnection of $\text{C-C}$ bond at the $\text{α}$ and $\text{β}$ carbon of the given compound and by reattaching an alkoxy leaving group yield two ester precursors. The ester on the left has no $\text{α}$ hydrogens and, therefore, the crossed Claisen reaction leads only to the target product. The base used is ${\left({\text{CH}}_{\text{3}}\right)}_{\text{3}}{\text{CO}}^{\text{-}}$ in DMF. But the base could also be ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{O}}^{\text{-}}$.

The crossed Claisen reaction in the forward direction would proceed as follows:

Conclusion

The Claisen and Dieckmann condensations are new $\text{C-C}$ bond forming reactions proceed under basic condition.

Interpretation Introduction

(d)

Interpretation:

The synthesis of given compound using a Claisen condensation is to be shown.

Concept introduction:

In Claisen condensation, ethyl ethanoate (ethyl acetate) is treated with sodium ethoxide, followed by acid work up, a $\text{β-keto }$ ester is produced. A successful Claisen condensation generally requires at least two $\text{α}$ protons on the initial ester. The first $\text{α}$ proton required to produce the enolate anion and second $\text{α}$ proton favor overall product and significant amount of $\text{β-keto }$ ester isolated. The Claisen condensation has the potential for an intramolecular reaction, ultimately producing a ring which is called a Dieckmann condensation. An intramolecular nucleophilic addition-elimination reaction on an ester occur if the enolate anion derives from the portion of a molecule characteristic of a ketone or aldehyde.

Answer to Problem 21.67P

The synthesis of given compound is shown below.

Explanation of Solution

The given compound is,

The disconnection of $\text{C-C}$ bond at the $\text{α}$ and $\text{β}$ carbon of the given compound and by reattaching an alkoxy leaving group yield two ester precursors. The ester on the right has no $\text{α}$ hydrogens and, therefore, the crossed Claisen reaction leads only to the target product. The base used is ${\left({\text{CH}}_{\text{3}}\right)}_{\text{3}}{\text{CO}}^{\text{-}}$ in DMF. But the base could also be ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{O}}^{\text{-}}$.

The crossed Claisen reaction in the forward direction would proceed as follows:

Conclusion

The Claisen and Dieckmann condensations are new $\text{C-C}$ bond forming reactions proceed under basic condition.