What is the absolute configuration of the following stereocenters?

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

Answer: (C)

Verified step by step guidance

1. Identify the stereocenters in the molecule. In the given image, there are two stereocenters labeled as I and II.
2. Assign priorities to the substituents attached to each stereocenter based on the Cahn-Ingold-Prelog priority rules. For stereocenter I, consider the groups: NH2, CHO, CH2COOH, and H. For stereocenter II, consider the groups: OH, CH2NH2, CH2COOH, and H.
3. For each stereocenter, arrange the substituents in order of decreasing priority. The highest priority group is determined by atomic number, with ties broken by considering the atoms bonded to the tied atoms.
4. Determine the configuration by orienting the molecule so that the lowest priority group (usually hydrogen) is pointing away from you. Trace a path from the highest priority substituent to the lowest, ignoring the lowest priority group.
5. If the path traced is clockwise, the configuration is R. If the path is counterclockwise, the configuration is S. Apply this method to both stereocenters I and II to determine their absolute configurations.