What is the absolute configuration of the following stereocenters?

• A. I: S, II: R
• B. I: S, II: S
• C. I: R, II: R
• D. I: R, II: S

Answer: (D)

Verified step by step guidance

1. Identify the stereocenters in the molecule. In the given structure, there are two stereocenters labeled as I and II.
2. For stereocenter I, assign priorities to the substituents based on atomic number. The substituents are OH, CH3, and the carbon chain leading to the SH group. Oxygen (OH) has the highest priority, followed by the carbon chain, and then CH3.
3. Orient the molecule so that the lowest priority group (CH3) is pointing away from you. Determine the order of the remaining groups (OH and the carbon chain) in a clockwise or counterclockwise direction.
4. For stereocenter II, repeat the process of assigning priorities. The substituents are SH, CH3, and the carbon chain leading to the OH group. Sulfur (SH) has the highest priority, followed by the carbon chain, and then CH3.
5. Orient the molecule so that the lowest priority group (CH3) is pointing away from you. Determine the order of the remaining groups (SH and the carbon chain) in a clockwise or counterclockwise direction. This will help you assign the absolute configuration as R or S for each stereocenter.