Chapter 11, Problem 11.77AP

Interpretation Introduction

(a)

Interpretation:

The curved arrow mechanism for the given reaction is to be shown.

Concept Introduction:

Neighbouring group participation is the interaction of the lone pair electrons of an atom (hetero) or electron present in sigma and pi bond with the parent molecule to increase the speed of the reaction. It is also known as anchimeric assistance.

Answer to Problem 11.77AP

The curved arrow mechanism for the reaction is shown below.

Explanation of Solution

The given reaction is shown below.

Figure 1

The oxygen atom of the alkoxide ion attack carbon of double bond to form epoxide ring. The carbocation is formed as an intermediate. Bromide ion reacts with the carbocation intermediate to form $\text{3-}\left(\text{bromomethyl}\right)\text{-2, 2-dimethyloxirane}$. The curved-arrow mechanism of the given reaction is shown below.

Figure 2

Conclusion

The curved arrow mechanism for given reaction is shown in Figure 2.

Interpretation Introduction

(b)

Interpretation:

The curved arrow mechanism for the given reaction is to be shown.

Concept Introduction:

Neighbouring group participation is -the interaction of the lone pair electrons of an atom (hetero) or electron present in sigma and pi bond with the parent molecule to increase the speed of the reaction. It is also known as anchimeric assistance.

Answer to Problem 11.77AP

The curved arrow mechanism for the given reaction is shown below.

Explanation of Solution

The given reaction is shown below.

Figure 3

Hydroxide ion abstract the proton from hydroxyl group of given compound. The oxide attacks the carbon of epoxide ring to form a five membered ring. The alkoxide ion formed is protonated in presence of water. The curved arrow mechanism of the given reaction is shown below.

Figure 4

Conclusion

The curved arrow mechanism for given reaction is shown in Figure 4.

Interpretation Introduction

(c)

Interpretation:

The curved arrow mechanism for the given reaction is to be shown.

Concept Introduction:

Neighbouring group participation is -the interaction of the lone pair electrons of an atom (hetero) or electron present in sigma and pi bond with the parent molecule to increase the speed of the reaction. It is also known as anchimeric assistance.

Answer to Problem 11.77AP

The curved arrow mechanism of the given reaction is shown below.

Explanation of Solution

The given reaction is shown below.

Figure 5

The methoxy group attacks the carbon containing sulfonate ester group. The nucleophilic displacement reaction occurs. The sulfonate ester group is displaced by methoxy group. Then neighbouring group participation of sulfur atom displaces the methoxy group. The sulfonium ion formed undergoes deprotonation to form the product. The curved arrow mechanism of the given reaction is shown below.

Figure 6

Conclusion

The curved arrow mechanism for given reaction is shown in Figure 6.

Interpretation Introduction

(d)

Interpretation:

The curved arrow mechanism for the given reaction is to be shown.

Concept Introduction:

Neighbouring group participation is -the interaction of the lone pair electrons of an atom (hetero) or electron present in sigma and pi bond with the parent molecule to increase the speed of the reaction. It is also known as anchimeric assistance.

Answer to Problem 11.77AP

The curved arrow mechanism of the given reaction is shown below.

Explanation of Solution

The given reaction is shown below.

Figure 7

A strong base is used in the reaction; hence elimination reaction will take place. The given compound contains two $\beta$ hydrogen atoms therefore two products can be formed. The base abstracts $\beta$ hydrogen atom, which result in carbon-carbon double bond formation and epoxide ring opening. The product $\text{2-methylbut-3-en-2-ol}$ is major product and $\text{3-methylbut-3-en-2-ol}$ is minor product. The curved arrow mechanism of the given reaction is shown below.

Figure 8

Conclusion

The curved arrow mechanism for given reaction is shown in Figure 8.

Interpretation Introduction

(e)

Interpretation:

The curved arrow mechanism for the given reaction is to be shown.

Concept Introduction:

Neighbouring group participation is -the interaction of the lone pair electrons of an atom (hetero) or electron present in sigma and pi bond with the parent molecule to increase the speed of the reaction. It is also known as anchimeric assistance.

Answer to Problem 11.77AP

The curved arrow mechanism of the given reaction is shown below.

Explanation of Solution

The given reaction is shown below.

Figure 9

The alkene undergoes addition reaction with the strong base. Then neighbouring group participation of sulfur atom takes place. The sulfur atom displaces the ${\text{F}}_{\text{3}}\text{C}{\text{O}}_{\text{2}}\text{SO}$ group resulting in formation of sulfonium ion. The curved arrow mechanism of the given reaction is shown below.

Figure 10

Conclusion

The curved arrow mechanism for given reaction is shown in Figure 10.

Interpretation Introduction

(f)

Interpretation:

The curved arrow mechanism for the given reaction is to be shown.

Concept Introduction:

Neighbouring group participation is -the interaction of the lone pair electrons of an atom (hetero) or electron present in sigma and pi bond with the parent molecule to increase the speed of the reaction. It is also known as anchimeric assistance.

Answer to Problem 11.77AP

The curved arrow mechanism of the given reaction is shown below.

Explanation of Solution

The given reaction is shown below.

Figure 11

The lone pair of sulphur atom attacks the carbon of methyl bromide. The sulfur atom of the ring gets methylated. Then bromide ion attacks the carbon atom of ring which results in ring opening to form the desired product. The curved arrow mechanism of the given reaction is shown below.

Figure 12

Conclusion

The curved arrow mechanism for given reaction is shown in Figure 12.

Interpretation Introduction

(g)

Interpretation:

The curved arrow mechanism for the given reaction is to be shown.

Concept Introduction:

Neighbouring group participation is -the interaction of the lone pair electrons of an atom (hetero) or electron present in sigma and pi bond with the parent molecule to increase the speed of the reaction. It is also known as anchimeric assistance.

Answer to Problem 11.77AP

The curved arrow mechanism of the given reaction is shown below.

Explanation of Solution

The given reaction is shown below.

Figure 13

The neighbouring group participation of oxygen atom takes place in the given reaction. The oxygen atom of hydroxyl group attacks the electrophilic carbon atom of the epoxide ring which results in the formation of new epoxide ring. Then cyanide ion attacks at the electrophilic carbon of epoxide which results in ring opening. The oxide ion takes proton form ethanol to form desired product. The curved arrow mechanism for given reaction is shown below.

Figure 14

Conclusion

The curved arrow mechanism for given reaction is shown in Figure 14.

Interpretation Introduction

(h)

Interpretation:

The curved arrow mechanism for the given reaction is to be shown.

Concept Introduction:

Neighbouring group participation is -the interaction of the lone pair electrons of an atom (hetero) or electron present in sigma and pi bond with the parent molecule to increase the speed of the reaction. It is also known as anchimeric assistance.

Answer to Problem 11.77AP

The curved arrow mechanism of the given reaction is shown below.

Explanation of Solution

The given reaction is shown below.

Figure 15

The sulfur atom attacks at the electrophilic carbon atom to form a four membered ring. The nucleophilic attack by methanol at the ring results in ring opening. Then the base abstracts proton from the protonated hydroxyl group to form the desired product. The curved-arrow mechanism for the given reaction is shown below.

Figure 16

Conclusion

The curved arrow mechanism for given rearrangement is shown in Figure 16.

Interpretation Introduction

(i)

Interpretation:

The curved arrow mechanism for the given reaction is to be shown.

Concept Introduction:

The vicinal diol compounds are cleaved by lead tetraacetate. The carbon-carbon of diol is cleaved. The vicinal diol are converted to aldehyde or ketone compounds using lead tetraacetate.

Answer to Problem 11.77AP

The curved arrow mechanism of the given reaction is shown below.

Explanation of Solution

Figure 17

The given compound is a vicinal diol. It will react with the lead tetraacetate to form five membered ring intermediate. The intermediate formed rearranges to form acetone, benzaldehyde and lead diacetate. The curved arrow mechanism for the given reaction is shown below.

Figure 18

Conclusion

The curved arrow mechanism for given reaction is shown in Figure 18.