Which of the following compound has `'S'` configuration?

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds has an 'S' configuration, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Groups**: Look at the Fischer projection of each compound and identify the four substituents attached to the chiral carbon atom. Label them as A, B, C, and D.

2. **Assign Priorities**: Assign priorities to the substituents based on the Cahn-Ingold-Prelog priority rules:
- The atom with the highest atomic number gets the highest priority (1).
- The atom with the lowest atomic number gets the lowest priority (4).
- If two atoms are the same, look at the next atoms in the substituent until a difference is found.

3. **Position the Lowest Priority Group**: Ensure that the lowest priority group (4) is positioned on the vertical line of the Fischer projection. This is crucial for determining the configuration correctly.

4. **Determine the Configuration**:
- Trace a path from the highest priority group (1) to the second highest (2) to the third highest (3).
- If the path is clockwise, the configuration is 'R'.
- If the path is counterclockwise, the configuration is 'S'.

5. **Analyze Each Compound**: Repeat the above steps for each compound provided in the question.

6. **Identify the Correct Compound**: The compound that shows an 'S' configuration based on the analysis will be your answer.

### Example Analysis:
- **Compound A**:
- Assign priorities: D (1), A (2), B (3), H (4).
- If the path from 1 to 2 to 3 is clockwise, it is 'R'.

- **Compound B**:
- Assign priorities: BR (1), O (2), CS3 (3), H (4).
- If the path from 1 to 2 to 3 is clockwise, it is 'R'.

- **Compound C**:
- Assign priorities: BR (1), O (2), H (3), CS3 (4).
- If the path from 1 to 2 to 3 is counterclockwise, it is 'S'.

- **Compound D**:
- Assign priorities: BR (1), O (2), H (3), CS3 (4).
- If the path from 1 to 2 to 3 is clockwise, it is 'R'.

### Conclusion:
After analyzing all the compounds, the compound that has an 'S' configuration is **Compound C**.