Question

Assign an R or S configuration to the chiral center in the following compound?

1) R configuration
2) S configuration

Answer 1

To assign the R or S configuration to a chiral center, prioritize the attached groups by atomic number, account for the orientation of the lowest priority group, and determine the direction of an arrow drawn from highest to lowest priority (excluding the lowest group). If the arrow is clockwise, it's R; if counterclockwise, it's S.

Step-by-step explanation:

To assign an R or S configuration to the chiral center in a compound, we follow these steps:

1. Assign priority based on the atomic number of atoms attached to the chiral center.
2. If the lowest priority group (#4) is pointing away from the viewer (on a hashed wedge or vertical line in Fisher projection), proceed to step 3. Otherwise, swap #4 with the group that is away from the viewer before proceeding.
3. Draw an arrow starting from the group with priority #1, then to #2, and finally to #3. If the arrow moves in a clockwise direction, the configuration is R; if it moves counterclockwise, the configuration is S.

For example, if the chiral center is attached to the following groups:

1. Priority 1: Br (bromine)
2. Priority 2: NH₂ (amine)
3. Priority 3: CH₃ (methyl group)
4. Priority 4: H (hydrogen, lowest priority)

And hydrogen is on the hashed wedge, drawing an arrow from Br to NH₂ to CH₃ if it moves in a counterclockwise manner, the configuration is S.