Question

Write short notes on the cyclic forms of ketose monosaccharides.

Answer 1

Ketose: A monosaccharide with one ketone group per molecule is called a ketose.

Cyclic structures of ketose monosaccharides:

• Due to the five-membered cyclic structure of ketoses (like fructose) is similar to furan, the cyclic structure of ketoses is called furanose.
• Depending on which way the anomeric hydroxy group is pointing, the furanose ring will have either an alpha or a beta structure.
• An enediol tautomeric intermediate facilitates the interconversion and subsequent epimerization at sites alpha to the carbonyl functionalities.