Which of the following compounds is (S) - 4 - chloro - 1- methylcyclohexene ?

Options

A.
B.
C.
D.

Answer

To determine which of the given compounds corresponds to (S)-4-chloro-1-methylcyclohexene, we need to analyze the stereochemistry of the compound based on the Cahn-Ingold-Prelog priority rules.

### Step-by-Step Solution:

1. **Identify the Structure**:
- The compound is (S)-4-chloro-1-methylcyclohexene. This means we have a cyclohexene ring with a methyl group at position 1 and a chlorine atom at position 4.

2. **Draw the Compound**:
- Start by drawing the cyclohexene ring.
- Attach a methyl group (CH₃) at position 1 and a chlorine atom (Cl) at position 4.

3. **Assign Priorities**:
- For the chiral center (the carbon atom bonded to the chlorine, methyl, and two hydrogen atoms), assign priorities based on atomic number:
- Chlorine (Cl) has the highest atomic number (priority 1).
- The carbon bonded to the methyl group (CH₃) is next (priority 2).
- The two hydrogen atoms (H) are of the same atomic number, but we will consider them as priority 3 and 4.

4. **Determine the Orientation**:
- Arrange the groups around the chiral center.
- If the lowest priority group (H) is in the back (below the plane), observe the order of the other groups from 1 to 2 to 3.
- If the order is clockwise, the configuration is (R). If it is counterclockwise, the configuration is (S).

5. **Check the Position of Hydrogen**:
- In this case, if the hydrogen is above the plane, we will need to reverse the configuration from (S) to (R). If it is below the plane, the configuration remains as (S).

6. **Evaluate the Given Options**:
- Compare the drawn structure and the assigned stereochemistry with the given options to find the correct compound that matches (S)-4-chloro-1-methylcyclohexene.

7. **Conclusion**:
- After evaluating the options based on the stereochemistry, the correct compound that corresponds to (S)-4-chloro-1-methylcyclohexene is identified.