Question

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

Short answer

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

Step-by-step solution

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:

$\mathrm{Number}\mathrm{of}\mathrm{stereoisomer}=2^{\mathrm{n}}$

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:

Structure of L-isoleucine

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

Stereoisomers of L-isoleucine

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