Let’s break down the reaction: ### Reactants: - **2-methylcyclohexene** - **Chloroform (CHCl₃)** - **Potassium tert-butoxide (t-BuOK)** --- ## Step 1: Understanding the Reaction This is a classic example of **carbene addition** (specifically, the formation of a **dichlorocarbene**, :CCl₂). **t-BuOK** is a strong base. It deprotonates **CHCl₃** to generate the **dichlorocarbene** (:CCl₂), which then adds to the double bond of the alkene (**2-methylcyclohexene**) to form a **cyclopropane ring** fused to the cyclohexane ring, with two Cl atoms on the newly formed cyclopropane. --- ## Step 2: Mechanism ### **A. Generation of Dichlorocarbene (:CCl₂)** **Step 1: Deprotonation of Chloroform** - **t-BuOK** abstracts a proton from **CHCl₃**, forming **trichloromethide anion (CCl₃⁻)** and **tert-butanol**. ``` CHCl₃ + t-BuOK → CCl₃⁻ + t-BuOH + K⁺ ``` **Arrow-pushing**: - Lone pair on O⁻ of t-BuO⁻ attacks the H of CHCl₃. - The C-H bond electrons move to the C, making CCl₃⁻. **Step 2: Loss of Cl⁻ to generate :CCl₂** - The CCl₃⁻ anion is unstable and eliminates **Cl⁻** to form **dichlorocarbene (:CCl₂)**. ``` CCl₃⁻ → :CCl₂ + Cl⁻ ``` **Arrow-pushing**: - Lone pair on C pushes out a Cl⁻, forming a neutral carbene (:CCl₂). --- ### **B. Addition of Dichlorocarbene to 2-Methylcyclohexene** - The **dichlorocarbene (:CCl₂)** adds to the double bond of **2-methylcyclohexene** in a **concerted cyclopropanation**. **Mechanism**: - The π electrons of the alkene attack the empty p-orbital of :CCl₂. - Simultaneously, a lone pair from :CCl₂ forms a bond to the other alkene carbon. - This forms a **bicyclo[4.1.0]heptane ring system** (the cyclohexane fused to a cyclopropane), and the two Cl atoms are attached to the same cyclopropane carbon. --- ## Step 3: Drawing the Mechanism ### **1. Generation of the carbene:** ``` :O⁻ t-Bu-O⁻ + CHCl₃ → t-Bu-OH + :CCl₃⁻ | :CCl₃⁻ → :CCl₂ + Cl⁻ ``` - Arrow from O⁻ to H of CHCl₃, arrow from C-H to C. - Arrow from lone pair on C to Cl, eliminating Cl⁻. ### **2. Carbene addition:** ``` 2-methylcyclohexene + :CCl₂ → (bicyclo[4.1.0]heptane derivative with two Cl on the cyclopropane ring) ``` - Arrow from alkene π bond to carbene C. - Lone pair from carbene forms bond to other alkene carbon. --- ## Step 4: Final Product **Name:** **1,1-dichloro-2-methylbicyclo[4.1.0]heptane** **Structure:** - A cyclohexane ring with a fused cyclopropane ring between C1 and C2. - The two Cl atoms are both on the C1 of the cyclopropane ring. - The methyl group is at C2. **Drawn Structure:** ``` (Methyl) | _____2 / \ / \ 1---------6 | | 7---------3 \ / \_____/ | Cl | Cl ``` - The cyclopropane is fused between C1 and C2. --- ## **Summary Table** | Step | Key Intermediate | Final Product | |--------------------|-----------------|--------------------------------------------------| | Carbene formation | :CCl₂ | 1,1-dichloro-2-methylbicyclo[4.1.0]heptane | --- ## **Curved Arrow Mechanism (Summary)** 1. **t-BuO⁻** deprotonates **CHCl₃** (arrow from O⁻ to H; arrow from C-H to C). 2. **CCl₃⁻** eliminates **Cl⁻** (arrow from lone pair on C to Cl). 3. **:CCl₂** adds to alkene (arrows from π bond to carbene C, and from carbene lone pair to other alkene carbon). --- ## **In words:** **2-methylcyclohexene** reacts with **chloroform** and **t-BuOK** to produce **1,1-dichloro-2-methylbicyclo[4.1.0]heptane** via a **dichlorocarbene addition**. The key intermediate is **dichlorocarbene (:CCl₂)**. --- **If you need a detailed hand-drawn mechanism, let me know!**

Certainly! Here's a detailed explanation with the key intermediate, the final product, and the curved arrow mechanism, including the stereochemistry (wedge and dash bonds). --- ### **Reaction Overview:** **Reactants:** - 2-methylcyclohexene (alkene with a methyl at C2) - Chloroform (CHCl₃) - Potassium tert-butoxide (t-BuOK) **Product:** - 1,1-dichloro-2-methylbicyclo[4.1.0]heptane --- ### **Step 1: Formation of Dichlorocarbene (:CCl₂)** **a. Deprotonation of chloroform:** - t-BuOK abstracts the acidic proton (H) from chloroform:  *Arrow:* Lone pair from O⁻ attacks H of CHCl₃, forming t-BuOH and CCl₃⁻. **b. Loss of chloride to form carbene:** - The trichloromethyl anion (CCl₃⁻) expels Cl⁻ to generate dichlorocarbene (:CCl₂):  *Arrow:* Lone pair on CCl₃⁻ attacks Cl, ejecting Cl⁻, leaving behind :CCl₂. --- ### **Step 2: Carbene addition to the alkene** - The carbene (:CCl₂) adds across the double bond of 2-methylcyclohexene, forming a cyclopropane fused to the cyclohexane ring. - **Mechanism:** - The π electrons of the alkene attack the carbene carbon (:CCl₂). - Simultaneously, the lone pair on carbene forms a bond with the other alkene carbon. - **Stereochemistry:** - The addition occurs **concertedly** and **stereospecifically**. - The two Cl atoms end up on the same face of the cyclopropane ring (cis addition) leading to the stereochemistry shown with wedge/dash bonds. --- ### **Step 3: Final Product** The product is **1,1-dichloro-2-methylbicyclo[4.1.0]heptane**. **Structural features:** - The cyclopropane ring is fused to the cyclohexane ring. - Both Cl atoms are attached to the same carbon of the cyclopropane (C-1). - The methyl group remains at C-2. - The stereochemistry (wedge/dash) indicates the Cl atoms are on the same face (cis). --- ### **Diagram of the Product (with stereochemistry):** ``` Cl (wedge) | ___ C (C-1) / \__/ | / | / | / | / /\/ / \ (Cyclohexane ring with methyl at C2) ``` - The two Cl atoms are both **wedged** (coming out of the plane), indicating they are **cis**. --- ### **Summary:** | Step | Key Intermediate | Final Product | |---------|---------------------|------------------------------| | Carbene formation | :CCl₂ | 1,1-dichloro-2-methylbicyclo[4.1.0]heptane | --- ### **Curved Arrow Summary:** 1. **Deprotonation of chloroform:** - Arrow from lone pair on O⁻ to H of CHCl₃. - Arrow from C-H bond to carbon, forming CCl₃⁻. 2. **Formation of carbene:** - Arrow from lone pair on CCl₃⁻ to Cl, ejecting Cl⁻. 3. **Addition to alkene:** - Arrow from π bond of alkene to carbene carbon. - Arrow from lone pair on carbene to the other alkene carbon. --- **This process results in the formation of a cyclopropane fused to a cyclohexane with two Cl substituents on the same face, giving the stereochemistry indicated by wedge bonds.** --- **Let me know if you'd like a hand-drawn sketch or further clarification!**