Chapter 26, Problem 26.43P

Devise a synthesis of each compound from benzene. You may also use any organic compounds having four carbons or fewer, and any required inorganic reagents.

a. b. c. d.

Interpretation Introduction

(a)

Interpretation: A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is to be stated.

Concept introduction: Cyclopropane can be formed by Smith reaction. The reaction of dihalocarbene with the alkene results in addition of carbene to the alkene and this addition takes place from either side of the plane.

Answer to Problem 26.43P

A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is,

Explanation of Solution

The synthesis of given compound involves three steps.

The first step is the Friedal craft alkylation reaction of benzene with ${\text{CH}}_{\text{3}}\text{Cl}$ in the presence of ${\text{AlCl}}_3$ to form toluene. The second step is the reaction of toluene with triphenylphosphine to form an ylide which further reacts with formaldehyde in next step to form styrene. In the last step, styrene reacts with ${\text{CH}}_{\text{2}}{\text{I}}_{\text{2}}$ in the presence of $\text{Zn}\left(\text{Cu}\right)$ to give the desired product. The steps for the formation of given product are shown below. These steps are shown below.

Figure 1

Conclusion

A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is shown in Figure 1.

Interpretation Introduction

(b)

Interpretation: A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is to be stated.

Concept introduction: The treatment of $\text{KOC}{\left({\text{CH}}_{\text{3}}\right)}_{\text{3}}$ with ${\text{CHX}}_{\text{3}}$, yields a dihalocarbene. The dihalocarbene is an electrophile that readily reacts with $\text{C}=\text{C}$ of an alkene to form a cyclopropane ring. This step leads to the formation of two new $\text{C}-\text{C}$ bonds.

Answer to Problem 26.43P

A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is,

Explanation of Solution

The synthesis of given compound involves four steps.

The first step is Friedel-Craft alkylation of benzene with ${\text{CH}}_{\text{3}}\text{Cl}$ in the presence of ${\text{AlCl}}_{\text{3}}$ catalyst to yield toluene. The second step is conversion of toluene to Wittig reagent by ${\text{PPh}}_{\text{3}}$ and base $\text{BuLi}$. The third step is treatment of obtained Wittig reagent with formaldehyde to yield styrene. The fourth step is treatment of styrene with dichlorocarbene that is formed by the reaction of $\text{KOC}{\left({\text{CH}}_{\text{3}}\right)}_{\text{3}}$ with ${\text{CHCl}}_{\text{3}}$, to yield the desired compound. These steps are shown below.

Figure 2

Conclusion

A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is shown in Figure 2.

Interpretation Introduction

(c)

Interpretation: A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is to be stated.

Concept introduction: The treatment of an organic halide with an alkene in the presence of $\text{Pd}$ catalyst to form an alkene that is highly substituted with a new $\text{C}-\text{C}$ bond is known as Heck reaction. Generally $\left[\text{Pd}{\left(\text{OAc}\right)}_2\right]$ in the presence of $\left[\text{P}{\left(o\text{-tolyl}\right)}_3\right]$ is utilized as catalyst. The reaction is carried out in the presence of organic base, like ${\text{Et}}_{\text{3}}\text{N}$.

Answer to Problem 26.43P

A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is,

Explanation of Solution

The synthesis of given compound involves two steps.

The first step is bromination of benzene with ${\text{Br}}_{\text{2}}$ in the presence of ${\text{FeBr}}_{\text{3}}$, a Lewis acid catalyst to yield bromobenzene. The second step is Heck reaction that is the treatment of an organic halide with an alkene in the presence of $\text{Pd}$ catalyst to form an alkene that is highly substituted with a new $\text{C}-\text{C}$ bond. Generally $\left[\text{Pd}{\left(\text{OAc}\right)}_2\right]$ in the presence of $\left[\text{P}{\left(o\text{-tolyl}\right)}_3\right]$ is utilized as catalyst. The reaction is carried out in the presence of organic base, like ${\text{Et}}_{\text{3}}\text{N}$. These steps are shown below.

Figure 3

Conclusion

A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is shown in Figure 3.

Interpretation Introduction

(d)

Interpretation: A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is to be stated.

Concept introduction: The treatment of an organic halide with an alkene in the presence of $\text{Pd}$ catalyst to form an alkene that is highly substituted with a new $\text{C}-\text{C}$ bond is known as Heck reaction. Generally $\left[\text{Pd}{\left(\text{OAc}\right)}_2\right]$ in the presence of $\left[\text{P}{\left(o\text{-tolyl}\right)}_3\right]$ is utilized as catalyst. The reaction is carried out in the presence of organic base, like ${\text{Et}}_{\text{3}}\text{N}$.

Answer to Problem 26.43P

A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is,

Explanation of Solution

The synthesis of given compound involves two steps.

The first step is bromination of benzene with ${\text{Br}}_{\text{2}}$ in the presence of ${\text{FeBr}}_{\text{3}}$, a Lewis acid catalyst to yield bromobenzene. The second step is Heck reaction that is the treatment of an organic halide with an alkene (propene) in the presence of $\text{Pd}$ catalyst to form an alkene that is highly substituted with a new $\text{C}-\text{C}$ bond. Generally $\left[\text{Pd}{\left(\text{OAc}\right)}_2\right]$ in the presence of $\left[\text{P}{\left(o\text{-tolyl}\right)}_3\right]$ is utilized as catalyst. The reaction is carried out in the presence of organic base, like ${\text{Et}}_{\text{3}}\text{N}$. These steps are shown below.

Figure 4

Conclusion

A synthesis of given compound from benzene, any organic compounds having four carbons or fewer, and any required inorganic reagents is shown in Figure 4.