In general a pyranose is any cyclic isomer that has a five carbons and one oxygen in a ring of six atoms. If a hydroxyl at the 5 position of an aldohexose, such as glucose, forms a hemiacetal with the aldehyde (position 1), the resulting isomer is glucopyranose. The hydroxyl group at position 1 is sterically undefined.
|D-glucose as its pyranose and aldose forms|
A pyranose structure with an undefined asymmetric center at position 1 represents both the α diastereomer and the β diastereomer. These two diastereomers have an indentical saccharide name, i.e. glucopyranose. The other hydroxyls at positions 2, 3, and 4, if changed, will result in a diastereomer with a different name. Pyranose monosaccharides are quite common in the literature—their conformation resembles the well-known cyclohexane system.
When there is more than one name for a pyranose, the name most often used in on top. Also where noted are other facts about the monosaccharide.