Question

Draw the other three stereoisomers of L-isoleucine, and label the stereogenic centers as R or S.

Short answer

Answer

Step-by-step solution

Step 1:Stereoisomers

Stereoisomers also have another designated name called spatial isomers. These isomers comprise equivalent molecular formulas but the atoms are positioned differently.

Stereogenic center

Stereogenic centres possessing R and S configuration are allocated based on the Cahn-Ingold Prelog rules.

On proceeding from higher priority to lower priority, the substituent in the clockwise direction is designated R. The substituent in the anticlockwise direction is designated as S.

Three stereoisomers of L-isoleucine and labelling the stereogenic centres

L-leucine possesses two stereogenic centres. The maximum number of stereoisomers are calculated using the formula:

Number of stereoisomers = 2ⁿ

Where n denotes the number of stereogenic centres. So the number of stereoisomers in isoleucine is 4.

The structure of L-isoleucine can be given as:

The other three stereoisomers of L-isoleucine with the labeled stereogenic centres are given as:

The R or S configuration for first, second and third stereoisomers are (2R,3R), (2R, 3S) and (2S, 3R).