Question

Draw the four stereoisomers of threonine as Fischer projections.

Short answer

The stereoisomers are the molecules with different configurations having at least one chiral center and the asymmetry of the chiral carbon results in two possible configurations.

Step-by-step solution

What are Stereoisomers?

The stereoisomers are the molecules with different configurations having at least one chiral center and the asymmetry of the chiral carbon results in two possible configurations.

Calculation of number of stereoisomers

If a molecule has n chiral centers, the number of stereoisomers can be calculated as 2ⁿwhere n$\mathbf{=}\mathbf{2}\mathbf{}\mathbf{for}\mathbf{}\mathbf{Threonine}$ Thus, there are 4 stereoisomers possible for threonine.

Fischer projection of Threonine

Thus, threonine has 4 Fischer projections.