For each pericyclic reaction below, write in the box whether the reaction is Diels-Alder, Electrocyclic, or Sigmatropic. Then fill in all mechanistic arrows for the forward (left to right) reaction.

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**Title: Understanding Pericyclic Reactions**

**Introduction**

Pericyclic reactions are a class of concerted chemical reactions that proceed via a cyclic transition state. They are generally categorized into three types: Diels-Alder, Electrocyclic, and Sigmatropic. Below are examples of these reactions. Your task is to identify each reaction type and draw the mechanistic arrows for the forward reaction.

**Example Reactions**

1. **Diels-Alder Reaction**
   - **Description**: This reaction typically involves a [4+2] cycloaddition between a conjugated diene and a dienophile, producing a cyclohexene ring.
   - **Reaction**:
     ```
     [Image: Benzene ring arrow to cyclohexane]
     ```
   - **Mechanism**: Draw arrows indicating the movement of electrons forming the new σ-bonds from the π-bonds of the diene and the dienophile.

2. **Electrocyclic Reaction**
   - **Description**: These reactions involve the conversion of a π-bonded system into a σ-bonded ring via a conrotatory or disrotatory motion.
   - **Reaction**:
     ```
     [Image: Cyclopentadiene arrow to pentane with π-bond]
     ```
   - **Mechanism**: Draw arrows showing the rotation and reorganization of π-electrons forming the new σ-bonds.

3. **Sigmatropic Rearrangements**
   - **Description**: Sigmatropic shifts involve the migration of a σ-bonded substituent from one position to another within the molecule, maintaining the π-electron system.
   - **Reaction**:
     ```
     [Image: Allyl vinyl ether arrow to cyclohexane with π-bond and substituent]
     ```
   - **Mechanism**: Illustrate the shift of the σ-bond and the reorganization of the π-electrons.

**Practice Task**

For each pericyclic reaction shown below, identify the reaction type (Diels-Alder, Electrocyclic, or Sigmatropic) and draw the mechanistic arrows for the forward (left to right) reaction.

1. Cyclohexadiene to cyclohexane
   ```
   [Image with blank box]
   ```

2. Cyclopentadiene with a π-bond to pentane with a π-bond and substituent
   ```
   [Image with blank box
Transcribed Image Text:**Title: Understanding Pericyclic Reactions** **Introduction** Pericyclic reactions are a class of concerted chemical reactions that proceed via a cyclic transition state. They are generally categorized into three types: Diels-Alder, Electrocyclic, and Sigmatropic. Below are examples of these reactions. Your task is to identify each reaction type and draw the mechanistic arrows for the forward reaction. **Example Reactions** 1. **Diels-Alder Reaction** - **Description**: This reaction typically involves a [4+2] cycloaddition between a conjugated diene and a dienophile, producing a cyclohexene ring. - **Reaction**: ``` [Image: Benzene ring arrow to cyclohexane] ``` - **Mechanism**: Draw arrows indicating the movement of electrons forming the new σ-bonds from the π-bonds of the diene and the dienophile. 2. **Electrocyclic Reaction** - **Description**: These reactions involve the conversion of a π-bonded system into a σ-bonded ring via a conrotatory or disrotatory motion. - **Reaction**: ``` [Image: Cyclopentadiene arrow to pentane with π-bond] ``` - **Mechanism**: Draw arrows showing the rotation and reorganization of π-electrons forming the new σ-bonds. 3. **Sigmatropic Rearrangements** - **Description**: Sigmatropic shifts involve the migration of a σ-bonded substituent from one position to another within the molecule, maintaining the π-electron system. - **Reaction**: ``` [Image: Allyl vinyl ether arrow to cyclohexane with π-bond and substituent] ``` - **Mechanism**: Illustrate the shift of the σ-bond and the reorganization of the π-electrons. **Practice Task** For each pericyclic reaction shown below, identify the reaction type (Diels-Alder, Electrocyclic, or Sigmatropic) and draw the mechanistic arrows for the forward (left to right) reaction. 1. Cyclohexadiene to cyclohexane ``` [Image with blank box] ``` 2. Cyclopentadiene with a π-bond to pentane with a π-bond and substituent ``` [Image with blank box
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