Chapter 28, Problem 23P

Draw the product of each of the following reactions:

Interpretation Introduction

Interpretation:

The product formed in the given reaction has to be drawn.

Concept introduction:

Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”.  There is a single transition state from start to finish, in contrast to a stepwise reaction.

There are mainly three types of pericyclic reactions,

1. 1) Pericyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

Woodward –Hoffmann rules are the set of rules used to vindicate or predict certain aspects of the stereo chemical outcome and activation energy of pericyclic reactions.

Woodward – Hoffmann rules for pericyclic reactions are listed below

A photochemical reaction takes place when a reactant absorbs light and a thermal reaction takes place without the absorption of light.

Woodward – Hoffmann rules for the configuration of pericyclic reactions are,

$\begin{array}{ccc}\text{Substituents}\text{in}\text{the}\text{reactant}& \text{Mode}\text{of}\text{ring}\text{closure}& \text{Configuration}\text{of}\text{the}\text{product}\\ \text{Point}\text{in}\text{opposite}\text{directions}& \text{Disrotatory}& \text{cis}\\ & \text{Conrotatory}& \text{trans}\\ \text{Point}\text{in}\text{the}\text{same}\text{directions}& \text{Disrotatory}& \text{trans}\\ & \text{Conrotatory}& \text{cis}\end{array}$

Answer to Problem 23P

Product formed in the given reaction is,

Explanation of Solution

Given reaction is,

Herein, the compound has an even number of $\Pi$ bonds, and then according to Woodward-Hoffmann rules, the compound will undergo conrotatory ring closure under thermal conditions.

Therefore the structure of the product formed in the reaction is,

Interpretation Introduction

Interpretation:

The product formed in the given reaction has to be drawn.

Concept introduction:

Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”.  There is a single transition state from start to finish, in contrast to a stepwise reaction.

There are mainly three types of pericyclic reactions,

1. 1) Pericyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

Woodward –Hoffmann rules are the set of rules used to vindicate or predict certain aspects of the stereo chemical outcome and activation energy of pericyclic reactions.

Woodward – Hoffmann rules for Pericyclic reactions are listed below

$\begin{array}{ccc}\text{Number}\text{of}\text{conjugated}\text{Π}\text{bonds}& \text{Reaction}\text{conditions}& \text{Allowed}\text{mode}\text{of}\text{ring}\text{closure}\\ \text{Even}\text{number}& \text{Thermal}& \text{Conrotatory}\\ & \text{Photochemical}& \text{Disrotatory}\\ \text{Odd}\text{number}& \text{Thermal}& \text{Disrotatory}\\ & \text{Photochemical}& \text{Conrotatory}\end{array}$

A photochemical reaction takes place when a reactant absorbs light and a thermal reaction takes place without the absorption of light.

Woodward – Hoffmann rules for the configuration of pericyclic reactions are,

$\begin{array}{ccc}\text{Substituents}\text{in}\text{the}\text{reactant}& \text{Mode}\text{of}\text{ring}\text{closure}& \text{Configuration}\text{of}\text{the}\text{product}\\ \text{Point}\text{in}\text{opposite}\text{directions}& \text{Disrotatory}& \text{cis}\\ & \text{Conrotatory}& \text{trans}\\ \text{Point}\text{in}\text{the}\text{same}\text{directions}& \text{Disrotatory}& \text{trans}\\ & \text{Conrotatory}& \text{cis}\end{array}$

Answer to Problem 23P

Product of given reaction is,

Explanation of Solution

Given reaction is,

Herein, the compound has an even number of $\Pi$ bonds, and then according to Woodward-Hoffmann rules, the compound will undergo conrotatory ring closure under thermal conditions.

Therefore the structure of the product formed in the reaction is,

Interpretation Introduction

Interpretation:

The product formed in the given reaction has to be drawn.

Concept introduction:

Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”.  There is a single transition state from start to finish, in contrast to a stepwise reaction.

There are mainly three types of pericyclic reactions,

1. 1) Pericyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

Woodward –Hoffmann rules are the set of rules used to vindicate or predict certain aspects of the stereo chemical outcome and activation energy of pericyclic reactions.

Woodward – Hoffmann rules for Pericyclic reactions are listed below

$\begin{array}{ccc}\text{Number}\text{of}\text{conjugated}\text{Π}\text{bonds}& \text{Reaction}\text{conditions}& \text{Allowed}\text{mode}\text{of}\text{ring}\text{closure}\\ \text{Even}\text{number}& \text{Thermal}& \text{Conrotatory}\\ & \text{Photochemical}& \text{Disrotatory}\\ \text{Odd}\text{number}& \text{Thermal}& \text{Disrotatory}\\ & \text{Photochemical}& \text{Conrotatory}\end{array}$

A photochemical reaction takes place when a reactant absorbs light and a thermal reaction takes place without the absorption of light.

Woodward – Hoffmann rules for the configuration of pericyclic reactions are,

$\begin{array}{ccc}\text{Substituents}\text{in}\text{the}\text{reactant}& \text{Mode}\text{of}\text{ring}\text{closure}& \text{Configuration}\text{of}\text{the}\text{product}\\ \text{Point}\text{in}\text{opposite}\text{directions}& \text{Disrotatory}& \text{cis}\\ & \text{Conrotatory}& \text{trans}\\ \text{Point}\text{in}\text{the}\text{same}\text{directions}& \text{Disrotatory}& \text{trans}\\ & \text{Conrotatory}& \text{cis}\end{array}$

Answer to Problem 23P

The product of the given reaction is,

Explanation of Solution

Given reaction is,

Here in the compound in which the four methyl substituent point in opposite directions, then according to Woodward-Hoffmann rules, they will be “cis” in the ring-closed product when ring closure is conrotatory and “trans” in the ring-closed product when ring closure is disrotatory.

Therefore the structure of the product formed in the reaction is,

Interpretation Introduction

Interpretation:

The product formed in the given reaction has to be drawn.

Concept introduction:

Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”.  There is a single transition state from start to finish, in contrast to a stepwise reaction.

There are mainly three types of pericyclic reactions,

1. 1) Pericyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

Woodward –Hoffmann rules are the set of rules used to vindicate or predict certain aspects of the stereo chemical outcome and activation energy of pericyclic reactions.

Woodward – Hoffmann rules for Pericyclic reactions are listed below

$\begin{array}{ccc}\text{Number}\text{of}\text{conjugated}\text{Π}\text{bonds}& \text{Reaction}\text{conditions}& \text{Allowed}\text{mode}\text{of}\text{ring}\text{closure}\\ \text{Even}\text{number}& \text{Thermal}& \text{Conrotatory}\\ & \text{Photochemical}& \text{Disrotatory}\\ \text{Odd}\text{number}& \text{Thermal}& \text{Disrotatory}\\ & \text{Photochemical}& \text{Conrotatory}\end{array}$

A photochemical reaction takes place when a reactant absorbs light and a thermal reaction takes place without the absorption of light.

Woodward – Hoffmann rules for the configuration of pericyclic reactions are,

$\begin{array}{ccc}\text{Substituents}\text{in}\text{the}\text{reactant}& \text{Mode}\text{of}\text{ring}\text{closure}& \text{Configuration}\text{of}\text{the}\text{product}\\ \text{Point}\text{in}\text{opposite}\text{directions}& \text{Disrotatory}& \text{cis}\\ & \text{Conrotatory}& \text{trans}\\ \text{Point}\text{in}\text{the}\text{same}\text{directions}& \text{Disrotatory}& \text{trans}\\ & \text{Conrotatory}& \text{cis}\end{array}$

Answer to Problem 23P

Product of the given reaction is,

Explanation of Solution

Given reaction is,

Here in the compound in which the two D and H substituent point in same directions, then according to Woodward-Hoffmann rules, they will be “trans” in the ring-closed product when ring closure is disrotatory and cis in the ring-closed product when ring closure is conrotatory.

Therefore the structure of the product formed in the reaction is,

Interpretation Introduction

Interpretation:

The product formed in the given reaction has to be drawn.

Concept introduction:

Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”.  There is a single transition state from start to finish, in contrast to a stepwise reaction.

There are mainly three types of pericyclic reactions,

1. 1) Pericyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

Woodward –Hoffmann rules are the set of rules used to vindicate or predict certain aspects of the stereo chemical outcome and activation energy of pericyclic reactions.

Woodward – Hoffmann rules for Pericyclic reactions are listed below

$\begin{array}{ccc}\text{Number}\text{of}\text{conjugated}\text{Π}\text{bonds}& \text{Reaction}\text{conditions}& \text{Allowed}\text{mode}\text{of}\text{ring}\text{closure}\\ \text{Even}\text{number}& \text{Thermal}& \text{Conrotatory}\\ & \text{Photochemical}& \text{Disrotatory}\\ \text{Odd}\text{number}& \text{Thermal}& \text{Disrotatory}\\ & \text{Photochemical}& \text{Conrotatory}\end{array}$

A photochemical reaction takes place when a reactant absorbs light and a thermal reaction takes place without the absorption of light.

Woodward – Hoffmann rules for the configuration of pericyclic reactions are,

$\begin{array}{ccc}\text{Substituents}\text{in}\text{the}\text{reactant}& \text{Mode}\text{of}\text{ring}\text{closure}& \text{Configuration}\text{of}\text{the}\text{product}\\ \text{Point}\text{in}\text{opposite}\text{directions}& \text{Disrotatory}& \text{cis}\\ & \text{Conrotatory}& \text{trans}\\ \text{Point}\text{in}\text{the}\text{same}\text{directions}& \text{Disrotatory}& \text{trans}\\ & \text{Conrotatory}& \text{cis}\end{array}$

Answer to Problem 23P

The product of given reaction is,

Explanation of Solution

Given reaction is,

Here in the compound have two $\Pi$ bonds and the two methyl substituent point in opposite directions, and then according to Woodward-Hoffmann rules, they will be “cis” in the ring-closed product when ring closure is disrotatory and cis in the ring-closed product when ring closure is conrotatory.

Therefore the structure of the product formed in the reaction is,

Interpretation Introduction

Interpretation:

The product formed in the given reaction has to be drawn.

Concept introduction:

Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”.  There is a single transition state from start to finish, in contrast to a stepwise reaction.

There are mainly three types of pericyclic reactions,

1. 1) Pericyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

Woodward –Hoffmann rules are the set of rules used to vindicate or predict certain aspects of the stereo chemical outcome and activation energy of pericyclic reactions.

Woodward – Hoffmann rules for Pericyclic reactions are listed below

$\begin{array}{ccc}\text{Number}\text{of}\text{conjugated}\text{Π}\text{bonds}& \text{Reaction}\text{conditions}& \text{Allowed}\text{mode}\text{of}\text{ring}\text{closure}\\ \text{Even}\text{number}& \text{Thermal}& \text{Conrotatory}\\ & \text{Photochemical}& \text{Disrotatory}\\ \text{Odd}\text{number}& \text{Thermal}& \text{Disrotatory}\\ & \text{Photochemical}& \text{Conrotatory}\end{array}$

A photochemical reaction takes place when a reactant absorbs light and a thermal reaction takes place without the absorption of light.

Woodward – Hoffmann rules for the configuration of pericyclic reactions are,

$\begin{array}{ccc}\text{Substituents}\text{in}\text{the}\text{reactant}& \text{Mode}\text{of}\text{ring}\text{closure}& \text{Configuration}\text{of}\text{the}\text{product}\\ \text{Point}\text{in}\text{opposite}\text{directions}& \text{Disrotatory}& \text{cis}\\ & \text{Conrotatory}& \text{trans}\\ \text{Point}\text{in}\text{the}\text{same}\text{directions}& \text{Disrotatory}& \text{trans}\\ & \text{Conrotatory}& \text{cis}\end{array}$

Answer to Problem 23P

Product of given reaction is,

Explanation of Solution

Given reaction is,

The reaction carried out under thermal conditions then according with the several Woodward - Hoffmann rules the probable structure formed in the given reaction is,

Interpretation Introduction

Interpretation:

The product formed in the given reaction has to be drawn.

Concept introduction:

Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”.  There is a single transition state from start to finish, in contrast to a stepwise reaction.

There are mainly three types of pericyclic reactions,

1. 1) Pericyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

Woodward –Hoffmann rules are the set of rules used to vindicate or predict certain aspects of the stereo chemical outcome and activation energy of pericyclic reactions.

Woodward – Hoffmann rules for Pericyclic reactions are listed below

$\begin{array}{ccc}\text{Number}\text{of}\text{conjugated}\text{Π}\text{bonds}& \text{Reaction}\text{conditions}& \text{Allowed}\text{mode}\text{of}\text{ring}\text{closure}\\ \text{Even}\text{number}& \text{Thermal}& \text{Conrotatory}\\ & \text{Photochemical}& \text{Disrotatory}\\ \text{Odd}\text{number}& \text{Thermal}& \text{Disrotatory}\\ & \text{Photochemical}& \text{Conrotatory}\end{array}$

A photochemical reaction takes place when a reactant absorbs light and a thermal reaction takes place without the absorption of light.

Woodward – Hoffmann rules for the configuration of pericyclic reactions are,

$\begin{array}{ccc}\text{Substituents}\text{in}\text{the}\text{reactant}& \text{Mode}\text{of}\text{ring}\text{closure}& \text{Configuration}\text{of}\text{the}\text{product}\\ \text{Point}\text{in}\text{opposite}\text{directions}& \text{Disrotatory}& \text{cis}\\ & \text{Conrotatory}& \text{trans}\\ \text{Point}\text{in}\text{the}\text{same}\text{directions}& \text{Disrotatory}& \text{trans}\\ & \text{Conrotatory}& \text{cis}\end{array}$

Answer to Problem 23P

The product of given reaction is,

Explanation of Solution

Given reaction is,

Here in the compound have two $\Pi$ bonds and the ring closure will be conrotatory according to Woodward-Hoffmann rules.  Therefore the structure of the product formed in the reaction is,

Interpretation Introduction

Interpretation:

The product formed in the given reaction has to be drawn.

Concept introduction:

Pericyclic reactions are “ any concerted reaction in which bonds are formed or brocken in a cyclic transition state”.  There is a single transition state from start to finish, in contrast to a stepwise reaction.

There are mainly three types of pericyclic reactions,

1. 1) Pericyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

Woodward –Hoffmann rules are the set of rules used to vindicate or predict certain aspects of the stereo chemical outcome and activation energy of pericyclic reactions.

Woodward – Hoffmann rules for Pericyclic reactions are listed below

$\begin{array}{ccc}\text{Number}\text{of}\text{conjugated}\text{Π}\text{bonds}& \text{Reaction}\text{conditions}& \text{Allowed}\text{mode}\text{of}\text{ring}\text{closure}\\ \text{Even}\text{number}& \text{Thermal}& \text{Conrotatory}\\ & \text{Photochemical}& \text{Disrotatory}\\ \text{Odd}\text{number}& \text{Thermal}& \text{Disrotatory}\\ & \text{Photochemical}& \text{Conrotatory}\end{array}$

A photochemical reaction takes place when a reactant absorbs light and a thermal reaction takes place without the absorption of light.

Woodward – Hoffmann rules for the configuration of pericyclic reactions are,

$\begin{array}{ccc}\text{Substituents}\text{in}\text{the}\text{reactant}& \text{Mode}\text{of}\text{ring}\text{closure}& \text{Configuration}\text{of}\text{the}\text{product}\\ \text{Point}\text{in}\text{opposite}\text{directions}& \text{Disrotatory}& \text{cis}\\ & \text{Conrotatory}& \text{trans}\\ \text{Point}\text{in}\text{the}\text{same}\text{directions}& \text{Disrotatory}& \text{trans}\\ & \text{Conrotatory}& \text{cis}\end{array}$

Answer to Problem 23P

Product of given reaction is,

Explanation of Solution

Given reaction is,

According to the Woodward-Hoffmann rules, the reactant coverts to product under thermal condition and the number of $\Pi$ bonds are same in both the reactant and product.

The structure of the product formed in the reaction is,