We are asked to identify the stereochemistry configuration of the given Ficher Projection.
We can see that this is a chiral molecule because:
– there is no plane of symmetry present
– there is a chiral center present
Recall that the R/S configuration gives us the absolute stereochemistry of chiral centers. It involves:
Step 1: Determine the priority of groups at the chiral center.
• Priority is determined using atomic mass.
• If the same atom is present, we compare the other atoms it is bonded to.
– Double and triple bonds count twice/thrice.
Step 2: Determine the R/S configuration of the chiral center.
• If the lowest priority is on a dashed line: trace a path from 1 to 3
– If the order is clockwise → R (rectus or right)
– If the order is counterclockwise → S (sinister or left)
Alanine is shown below as a Fischer projection. Identify the stereochemistry configuration.
Which Fischer structures below have the same stereochemistry configuration?