Continued from 2-Carb-27 and 2-Carb-28
The compounds obtained by transforming the carbonyl group of the acyclic form of a saccharide, or saccharide derivative, into the grouping:
are named as indicated in 2-Carb-30, by using the terms 'hemiacetal', 'monothiohemiacetal', or 'dithiohemiacetal'(or the corresponding 'hemiketal' terms for ketone derivatives), as appropriate. The two isomers of a monothiohemiacetal are differentiated by use of O and S prefixes.
(1S)-2,3,4,5,6-Penta-O-benzoyl-D-glucose ethyl dithiohemiacetal
(1R)-2,3,4,5,6-Penta-O-benzoyl-D-glucose O-ethyl monothiohemiacetal
(1S)-2,3,4,5,6-Penta-O-benzoyl-D-glucose S-ethyl monothiohemiacetal
Note. In these compounds carbon atom number 1 has become chiral. When known, the stereochemistry at this new chiral centre is indicated using the R,S system (, Section E).
2-Carb-30. Acetals, ketals and their thio analogues
The compounds obtained by transforming the carbonyl group of a saccharide or saccharide derivative into the grouping:
are named by placing after the name of the saccharide or saccharide derivative the term 'acetal', 'monothioacetal' or 'dithioacetal' (or the corresponding 'ketal' terms for ketone derivatives) as appropriate, preceded by the names of the groups R1 and R2. With monothioacetals, the mode of bonding of two different groups R1 and R2 is indicated by the use of the prefixes O and S.
D-Fructose diethyl ketal
D-Glucose propane-1,3-diyl dithioacetal
(1R)-2,3,4,5,6-Penta-O-acetyl-D-glucose dimethyl monothioacetal
Note. In the last two examples, carbon atom 1 has become chiral. When known, the stereochemistry at this new chiral centre is indicated by the R,S system, as specified in 2-Carb-29.
13. IUPAC Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F and H, 1979 Edition, Pergamon Press, Oxford, U.K. Sections E and F are reprinted in ref. 2, pp. 1-18 and 19-26, respectively.
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