Question

Indicate the stereochemical configuration for the tetrahedral centers shown below. R S not a configuration center Site 1 R S not a configuration center Site 2 R S not a configuration center

Indicate the stereochemical configuration for the tetrahedral centers shown below

Answer 1

Concepts and reason

An atom which is attached to four different groups is called as chiral. Assign R and S configuration at chiral center by using Cahn-Ingold-Prelog rules.

Fundamentals

Rules for assigning R and S configuration are,

Give priority order to the groups that are around the chiral carbon (i.e. the atom with higher atomic number gets higher priority).

Connect the highest priority group to the third highest priority group through an arrow. And 4^th highest priority groups must be in out of the plane (i.e. dashed bond).

If an arrow rotating in clockwise direction, then the configuration at chiral center is R.

If an arrow rotating in anticlockwise direction, then the configuration at chiral center is S.

Assign R/S configuration at chiral center by giving priority order to the groups that are around the chiral carbon.

Configuration at chiral center is S

Assign R/S configuration at chiral center by giving priority order to the groups that are around the chiral carbon.

Ans:

Thus, the configuration at chiral center is S.

Thus, the configuration at site 1 is R and configuration at site 2 is not a configuration center.