Chapter 12, Problem 12.2P

Interpretation Introduction

(a)

Interpretation:

How the given compound can be produced from an alkene is to be shown.

Concept introduction:

Electrophilic addition of carbenes to alkenes form cyclopropane rings. In carbine, the carbon atom has two bonds and a lone pair of electrons.

Carbenes are typically highly electrophilic due to the lack of an octet and are ${\text{sp}}^{\text{2}}$ hybridized. The lone pair of electrons in carbenes occupy a hybrid orbital, leaving the p orbital empty. Thus, carbenes resemble carbocations and are extremely electron-deficient. Diazomethane, ${\text{CH}}_{\text{2}}{\text{N}}_{\text{2}}$ is a precursor from which a carbene can be made. In an electrophilic addition reaction, alkenes react with carbenes forming a three‐membered ring. In this reaction the addition of the alkene to an electrophilic carbine takes place and at the same time, that lone pair can donate back so that a carbocation does not actually form. The stereochemistry of the substituents in the alkene is conserved in the product.

Answer to Problem 12.2P

The given compound can be produced from an alkene is shown below:

Explanation of Solution

The given compound is:

Electrophilic addition of carbenes to alkenes forms cyclopropane rings. Diazomethane (${\text{CH}}_{\text{2}}{\text{N}}_{\text{2}}$) is a precursor to produce carbene. Diazomethane, when heated, produces a carbene reactive intermediate.

This carbene intermediate reacts with an alkene in a concerted one-step reaction to form a cyclopropyl ring. The bridge carbon atom in the cyclopropyl ring comes from the carbene while the two carbon atoms are from the original alkene. Two new $\text{σ}$ $\text{C-C}$ bonds are formed simultaneously as one $\text{C=C}$$\text{π}$ bond is broken and a cyclopropane ring is formed. The stereochemistry of the substituents in the original alkene is conserved in the product. Note that, in the given product, the two methyl groups are trans to each other. This suggests that these two groups must be trans to each other too in the original alkene. Thus, the original alkene that has been used to form the given product is:

The complete reaction of the addition of carbene to alkene is shown below:

Conclusion

The given compound is produced via an electrophilic addition reaction of a carbene to an alkene.

Interpretation Introduction

(b)

Interpretation:

How the given compound can be produced from an alkene is to be shown.

Concept introduction:

Electrophilic addition of carbenes to alkenes forms cyclopropane rings. In carbine, the carbon atom has two bonds and a lone pair of electrons.

Carbenes are typically highly electrophilic due to the lack of an octet and are ${\text{sp}}^{\text{2}}$ hybridized. The lone pair of electrons in carbenes occupy a hybrid orbital, leaving the p orbital empty. Thus, carbenes resemble carbocations and are extremely electron-deficient. Diazomethane, ${\text{CH}}_{\text{2}}{\text{N}}_{\text{2}}$ is a precursor from which a carbene can be made. In an electrophilic addition reaction, alkenes react with carbenes forming a three‐membered ring. In this reaction the addition of the alkene to an electrophilic carbine takes place and at the same time, that lone pair can donate back so that a carbocation does not actually form. The stereochemistry of the substituents in the alkene is conserved in the product.

Answer to Problem 12.2P

The given compound can be produced from an alkene is shown below:

Explanation of Solution

The given compound is:

Electrophilic addition of carbenes to alkenes forms cyclopropane rings. Diazomethane (${\text{CH}}_{\text{2}}{\text{N}}_{\text{2}}$) is a precursor to produce a carbene. Diazomethane when heated produces a carbene reactive intermediate.

This carbene intermediate reacts with an alkene in a concerted one-step reaction to form a cyclopropyl ring. The bridge carbon atom in the cyclopropyl ring comes from the carbene while the two carbon atoms are from the original alkene. Two new $\text{σ}$ $\text{C-C}$ bonds are formed simultaneously as one $\text{C=C}$$\text{π}$ bond is broken and a cyclopropane ring is formed. The stereochemistry of the substituents in the original alkene is conserved in the product. Note that, in the given product, the two methyl groups are on the same side of the ring (cis). This suggests that these two groups in the alkene must be cis to each other. Thus, the original alkene that has been used to form the given product is:

The complete reaction of the addition of carbene to alkene is shown below:

Conclusion

The given compound is produced via an electrophilic addition reaction of a carbene to an alkene.

Interpretation Introduction

(c)

Interpretation:

How the given compound can be produced from an alkene is to be shown.

Concept introduction:

Electrophilic addition of carbenes to alkenes form cyclopropane rings. In carbine, the carbon atom has two bonds and a lone pair of electrons.

Carbenes are typically highly electrophilic due to the lack of an octet and are ${\text{sp}}^{\text{2}}$ hybridized. The lone pair of electrons in carbenes occupy a hybrid orbital, leaving the p orbital empty. Thus, carbenes resemble carbocations and are extremely electron-deficient. Diazomethane, ${\text{CH}}_{\text{2}}{\text{N}}_{\text{2}}$ is a precursor from which a carbene can be made. In an electrophilic addition reaction, alkenes react with carbenes forming a three‐membered ring. In this reaction the addition of the alkene to an electrophilic carbine takes place and at the same time, that lone pair can donate back so that a carbocation does not actually form. The stereochemistry of the substituents in the alkene is conserved in the product.

Answer to Problem 12.2P

The given compound can be produced from an alkene is shown below:

Explanation of Solution

The given compound is:

Electrophilic addition of carbenes to alkenes forms cyclopropane rings. Diazomethane (${\text{CH}}_{\text{2}}{\text{N}}_{\text{2}}$) is a precursor to produce carbene. Diazomethane, when heated, produces a carbene reactive intermediate.

This carbene intermediate reacts with an alkene in a concerted one-step reaction to form a cyclopropyl ring. The bridge carbon atom in the cyclopropyl ring comes from the carbene while the two carbon atoms are from the original alkene. Two new $\text{σ}$ $\text{C-C}$ bonds are formed simultaneously as one $\text{C=C}$$\text{π}$ bond is broken and a cyclopropane ring is formed. The stereochemistry of the substituents in the original alkene is conserved in the product. Note that the cyclopropyl ring that has formed is in the plane. Thus, the original alkene that has been used to form the given product is:

The complete reaction of the addition of carbene to alkene is shown below:

Conclusion

The given compound is produced via an electrophilic addition reaction of a carbene to an alkene.

Interpretation Introduction

(d)

Interpretation:

How the given compound can be produced from an alkene is to be shown.

Concept introduction:

Electrophilic addition of carbenes to alkenes forms cyclopropane rings. In carbine, the carbon atom has two bonds and a lone pair of electrons.

Carbenes are typically highly electrophilic due to the lack of an octet and are ${\text{sp}}^{\text{2}}$ hybridized. The lone pair of electrons in carbenes occupy a hybrid orbital, leaving the p orbital empty. Thus, carbenes resemble carbocations and are extremely electron-deficient. Diazomethane, ${\text{CH}}_{\text{2}}{\text{N}}_{\text{2}}$ is a precursor from which a carbene can be made. In an electrophilic addition reaction, alkenes react with carbenes forming a three‐membered ring. In this reaction the addition of the alkene to an electrophilic carbine takes place and at the same time, that lone pair can donate back so that a carbocation does not actually form. The stereochemistry of the substituents in the alkene is conserved in the product.

Answer to Problem 12.2P

The given compound can be produced from an alkene is shown below:

Explanation of Solution

The given compound is:

Electrophilic addition of carbenes to alkenes forms cyclopropane rings. Diazomethane (${\text{CH}}_{\text{2}}{\text{N}}_{\text{2}}$) is a precursor to produce a carbene. Diazomethane, when heated, produces a carbene reactive intermediate.

This carbene intermediate reacts with an alkene in a concerted one-step reaction to form a cyclopropyl ring. The bridge carbon atom in the cyclopropyl ring comes from the carbene while the two carbon atoms are from the original alkene. Two new $\text{σ}$ $\text{C-C}$ bonds are formed simultaneously as one $\text{C=C}$$\text{π}$ bond is broken and a cyclopropane ring is formed. The stereochemistry of the substituents in the original alkene is conserved in the product. Note that the cyclopropyl ring that has formed is in the plane. Thus, the original alkene that has been used to form the given product is:

The complete reaction of the addition of carbene to alkene is shown below:

Conclusion

The given compound is produced via an electrophilic addition reaction of a carbene to an alkene.