Which of the following compounds are known as threose and erythrose?

Options

A. `C_(4)`sugars
B. `C_(3)`sugars
C. `C_(5)`sugars
D. `C_(6)`sugars

Answer

A

Explanation

The `C_(4)` sugars with the different chiral centres exist in four enantiomerc forms and as two racemic mixtures. These are known as threose and erythrose and have Fisher projections `I-IV`

Erythrose exists in two enantiomeric forms `(I` and`II)` as does threose `(III` and `IV`). The compounds represented by `I` and `III` (or `IV`) are diastereoisomers. They are stereoismers which are not enantiomeric.