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Suppose I had a monosaccharide, e.g. D-arabinose. Suppose I do a few synthetic steps with it, and end up with the compound methyl (2S,3R,4R)-3,5-dihydroxy-2,4-dimethoxypentanoate. (as labelled by ChemDraw. If that is not the PIN, please correct.)

However, when writing my paper/thesis/lab report, I would love to derive the base name from D-arabinose for simplicity and consistency. The monosaccharide derivatives with a carboxylic acid in place of an aldehyde are -onic acids so my base name would be methyl D-arabinonate. But how would I correctly and unambiguously label the methoxy groups?

If I used 2,4-dimethyl, that would sound like this second compound:

And if I used 2,4-dimethoxy, wouldn’t that make it this one:

Is there a trick I am missing for clearly naming the compound as above with methyl D-arabinonate as a base name?

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  • $\begingroup$ Did you have a look at Pure Appl. Chem., 1996, 68, 1919-2008 IUPAC? $\endgroup$ – Klaus-Dieter Warzecha Feb 4 '16 at 16:00
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    $\begingroup$ @KlausWarzecha No, because I didn’t know it existed ^^' $\endgroup$ – Jan Feb 4 '16 at 16:34
  • $\begingroup$ How about methyl 2O, 4O-dimethylarabinoate? $\endgroup$ – Curt F. Feb 4 '16 at 16:45
  • $\begingroup$ @CurtF. After skimming across Klaus’ source, yeah, something like that. If someone who had previous experience in doing so could answer, that would be great ^^ $\endgroup$ – Jan Feb 4 '16 at 16:59
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It is possible to name such compounds based on retained carbohydrate names in accordance with the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) as follows.

P-102.5.6 Monosaccharide derivatives

P-102.5.6.1 O-Substitution

In order to maintain the integrity of structures and take advantage of retained names to imply the absolute configuration, O-substitution is allowed in carbohydrate nomenclature. Substituents replacing the hydrogen atom of an alcoholic hydroxy group of a monosaccharide or monosaccharide derivative are denoted as O-substituents. The substitution of an anomeric hydroxy group is discussed in P-102.5.6.3.2. The O-locant is not repeated for multiple substitution 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 atoms or groups.

P-102.5.6.1.1 O-Acetyl and O-alkyl functionalization.

For O-acyl derivatives, names with the acid component cited as a separate word ending in ‘ate’ after the monosaccharide name are preferred to names using O-acyl group prefixes. However when the ose ending is changed (e.g. to denote a glycosyl or an acid function having seniority over an ester) O-acyl prefixes are required. O-Alkyl derivatives are always expressed by prefixes.

Therefore, the name for the corrsponding D-arabinose derivative with methyl substituents replacing the hydrogen atoms of two alcoholic hydroxy group is 2,4-di-O-methyl-D-arabinose.

D-arabinose    2,4-di-O-methyl-D-arabinose

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