On this page the D-aldoses up to the hexoses are shown. There is only one D-triose, two D-tetroses, four D-pentoses, and eight D-hexoses. Structures in different rows will have a different number of CHOH groups. Any two structures within the same row (except for trioses) of D-aldoses will be diastereomers.
The simplest aldose is glyceraldehyde. Glyceraldehyde (also called glycerose) is a three-carbon aldose (triose). With one asymmetric center there are only two stereoisomers. This pair of stereoisomers are the enantionmers D- and L-glyceraldehyde. The D/L designation of all other carboydrates is based upon its similarity to the stereocenter in glyceraldehyde. If the highest numbered asymmetric carbon of a monosaccharide matches that of D-glyceraldehyde, then the saccharide is also of the D- configuration. In the chart below, the highest asymmetric carbon is towards the bottom with the aldehyde beginning as '1'.