Chapter 26, Problem 26.49P

Devise a synthesis of each of the following compounds. Besides inorganic reagents, you may use hydrocarbons and halides having $\le \text{6 C`s}$, and ${\text{CH}}_{\text{2}}={\text{CHCOOCH}}_{\text{3}}$ as starting materials. Each synthesis must use at least one of the carbon–carbon bond-forming reactions in this chapter.

a. c. e.

b. d. f.

Interpretation Introduction

(a)

Interpretation: The synthesis of the given compound is to be devised.

Concept introduction: Lithium aluminum hydride is a strong reducing agent. Treatment of carbonyl compounds with lithium aluminum hydride yields alcohols. It reduces ketone into secondary alcohol.

Answer to Problem 26.49P

The synthesis of the given compound is,

Explanation of Solution

The synthesis of given compound is follows:

Step-1 Chlorination of benzene takes place in the presence of ferric chloride and gives chlorobenzene.

Step-2 Chlorobenzene is treated with base and undergoes nucleophilic substitution reaction and gives phenol.

Step-3 Phenol is treated with methyl iodide and gives anisole.

Step-4 Anisole is treated with $\text{CuI}$ and lithium metal (two equivalents) and gives organocuprate compound.

Step-5 Organocuprate compound is treated with $\text{6-bromohexan-2-one}$ and gives a substituted product.

Step-6 The substituted product is treated with ${\text{LiAlH}}_{\text{4}}$ which reduce carbonyl to alcohol and gives a desired product.

The synthesis of the given compound is shown below.

Figure 1

Conclusion

The synthesis of given compound is shown in Figure 1.

Interpretation Introduction

(b)

Interpretation: The synthesis of the given compound is to be devised.

Concept introduction: Gilman reagents are organometallic compounds which are a source of nucleophiles. These nucleophiles give $\text{1, 4-}$ addition on $\text{α,β-}$ unsaturated carbonyl compounds. In $\text{1, 4-}$ addition reaction, the hydrogen and alkyl group is added to $\text{α}$ and $\text{β}$ carbons to carbonyl group, respectively.

Answer to Problem 26.49P

The synthesis of the given compound is,

Explanation of Solution

The synthesis of the given compound is follows:

Step-1 Alkene is treated with ${\text{Br}}_{\text{2}}$ to give $\text{1, 2-dibromoethane}$.

Step-2 $\text{1, 2-dibromoethane}$ is treated with Gilman’s reagent to give $\text{6-bromohex-1-ene}$.

Step-3The $\text{6-bromohex-1-ene}$ is treated with ${\text{OsO}}_{\text{4}}$ which leads to the cis addition of hydroxyl group at double bond.

Step-4 The compound obtained from step-4 is treated with ${\text{BuLi, PPh}}_{\text{3}}$ to give Wittig reagent.

Step-5 The Wittig reagent is treated with acetone to give a desired product.

The synthesis of the given compound is shown below.

Figure 2

Conclusion

The synthesis of the given compound is shown in Figure 2.

Interpretation Introduction

(c)

Interpretation: The synthesis of the given compound is to be devised.

Concept introduction: Suzuki reaction is a type of substitution reaction. It involves the palladium coupling between organic halide with organoborane in the presence of base. It is a stereospecific reaction.

Answer to Problem 26.49P

The synthesis of the given compound is,

Explanation of Solution

The synthesis of the given compound is follows:

Step-1 Hydroboration of hex $\text{-1-}$ yne with catechol borane takes place and gives $E\text{-}$ vinylborane.

Step-2 The $E\text{-}$ vinylborane is coupled with $\left(Z\right)\text{-2-bromopent-2-ene}$ and gives a desired $\text{1, 3-diene}$ product. Both the configuration $\left(E,Z\right)$ are retained in the product.

The synthesis of the given compound is shown below.

Figure 3

Conclusion

The synthesis of the given compound is shown in Figure 3.

Interpretation Introduction

(d)

Interpretation: The synthesis of the given compound is to be devised.

Concept introduction: Heck reaction is a type of substitution reaction. It involves the palladium coupling between aryl or vinyl halide with alkene which leads to the formation of trans alkene at less substituted carbon.

Answer to Problem 26.49P

The synthesis of the given compound is,

Explanation of Solution

The synthesis of the given compound is follows:

Step-1 Bromination of benzene takes place in the presence of ferric chloride and gives bromobenzene.

Step-2 Friedelcraft alkylation of bromobenzene takes place in the presence of isopropyl chloride.

Step-3The $\text{1-bromo-4-isopropylbenzene}$ is treated with ${\text{CH}}_{\text{2}}={\text{CHCOOCH}}_{\text{3}}$ in the presence of palladium catalyst undergoes Heck reaction and forms a desired product.

The synthesis of the given compound is shown below.

Figure 4

Conclusion

The synthesis of the given compound is shown in Figure 4.

Interpretation Introduction

(e)

Interpretation: The synthesis of the given compound is to be devised.

Concept introduction: Heck reaction is a type of substitution reaction. It involves the palladium coupling between aryl or vinyl halide with alkene which leads to the formation of trans alkene at less substituted carbon. The nonhalogenated cyclopropanes are synthesized by the treatment of an alkene with ${\text{CH}}_{\text{2}}{\text{I}}_{\text{2}}$, in the presence of zinc-copper couple $\left[\text{Zn}\left(\text{Cu}\right)\right]$. This process is known as Simmons-Smith reaction.

Answer to Problem 26.49P

The synthesis of given compound is,

Explanation of Solution

The synthesis of given compound is as follows:

Step-1 Bromobenzene is treated with ${\text{CH}}_{\text{2}}={\text{CHCOOCH}}_{\text{3}}$ in the presence of palladium catalyst undergoes Heck reaction and forms substituted trans alkene.

Step-2 The compound formed in step-1 undergoes Simmons-Smith reaction and forms a desired product.

The synthesis of the given compound is shown below.

Figure 5

Conclusion

The synthesis of given compound is shown in Figure 5.

Interpretation Introduction

(f)

Interpretation: The synthesis of given compound is to be devised.

Concept introduction: Heck reaction is a type of substitution reaction. It involves the palladium coupling between aryl or vinyl halide with alkene which leads to the formation of trans alkene at less substituted carbon.

Answer to Problem 26.49P

The synthesis of given compounds is,

Explanation of Solution

The synthesis of given compounds is as follows:

Step-1 Cyclohexane is treated with ${\text{Br}}_{\text{2}}$ in the presence of light to form brominated compound.

Step-2 The brominated compound then treated with $2\text{equivalents}$ of lithium and $0.5\text{equiv}$ copper iodide to form a organocuprate compound.

Step-3 The organocuprate compound then treated with organic bromide to form ethylcyclohexane.

Step-4 Then ethylcyclohexane undergoes heck reaction in the presence of 1-propene to form substituted alkene compound.

Step-5 The substituted alkene compound reacts with hydrogen peroxide in the sodium hydroxide to form the desired oxirane product.

The synthesis of the given compound is shown below.

Figure 6

Conclusion

The synthesis of given compound is shown in Figure 6.