Carb-24. O-Substitution

Substituents replacing the hydrogen atom of an alcoholic hydroxy group of a saccharide or saccharide derivative are denoted as O-substituents. The 0- locant is not repeated for multiple replacements by the same atom or group. Number locants are used as necessary to specify the positions of substituents they are not required for compounds fully substituted by identical groups. Alternative periphrase names for esters, ethers, etc. may be useful for indexing purposes. For cyclic acetals see 2-Carb-28. 

Penta-O-acetyl-a/de/iycfo-D-glucose 2,4-Di-0-acetyl-6-0-trityl-D-glucopyranose or a/dehydo-D-glucose pentaacetate 

Acyl substituents on anomeric OH are designated (as above) by 0-acyl prefixes. However, anomeric 0-alkyl derivatives are named as glycosides (see 2-Carb-33). 

Of special biochemical importance are the esters of monosaccharides with phosphoric acid. They are generally termed phosphates (e.g. glucose 6-phosphate). In biochemical use, the term phosphate indicates the phosphate residue regardless of the state of ionization or the counter ions. 

The prefix terms used for phosphate esters in organic nomenclature ([14], p.65) are 0-phosphono- and O-phosphonato- for the groups (H0)2P(0)- and (0 )2P(0)-respectively, bonded to oxygen. 

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