Aldohexose

An aldohexose is a hexose with an aldehyde group on one end.

The aldohexoses have four chiral centres for a total of 16 possible aldohexose stereoisomers (24). Of these, only three commonly occur in nature: D -glucose, D -galactose, and D -mannose. The D / L configuration is based on the orientation of the hydroxyl at position 3, and does not refer to the direction of optical activity.

There are eight D -aldohexoses:

CH=O          CH=O          CH=O            CH=O |             |             |               |   HC-OH        HO-CH           HC-OH         HO-CH |             |             |               |   HC-OH          HC-OH       HO-CH           HO-CH |             |             |               |   HC-OH          HC-OH         HC-OH           HC-OH |             |             |               |   HC-OH          HC-OH         HC-OH           HC-OH |             |             |               |    CH2-OH         CH2-OH        CH2-OH          CH2-OH D -Allose     D -Altrose     D -Glucose      D -Mannose

CH=O       CH=O            CH=O            CH=O |          |               |               |   HC-OH     HO-CH             HC-OH         HO-CH |          |               |               |   HC-OH       HC-OH         HO-CH           HO-CH |          |               |               | HO-CH       HO-CH           HO-CH           HO-CH |          |               |               |   HC-OH       HC-OH           HC-OH           HC-OH |          |               |               |    CH2-OH      CH2-OH          CH2-OH          CH2-OH D -Gulose   D -Idose       D -Galactose        D -Talose

Deoxyaldohexoses
Aldohexoses can have one or more of their hydroxyl groups replaced by hydrogens to form deoxyaldohexoses. The following are well known cases of such compounds :
 * L-Fucose (6-deoxy-L-galactose)
 * L-Rhamnose (6-deoxy-L-mannose)
 * D-Quinovose (6-deoxy-D-glucose) Quinovose is found as part of the sulfolipid SQDG.
 * L-Pneumose (6-deoxy-L-talose)

Hexosen Aldohexose