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What chain(s) of reactions are used to produce ʟ-glucose? I did a search on Google Scholar, but to my surprise nothing came up. My guess would be that the synthesis starts from ᴅ-glucose for which there are abundant natural sources. References would of course be highly appreciated!

andselisk
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frapadingue
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    Deleting my previous comment and eating my words: http://www.nrcresearchpress.com/doi/pdf/10.1139/v84-112 – Zhe Jan 25 '19 at 12:55
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    The Wikipedia page can be a good start: https://en.wikipedia.org/wiki/L-Glucose – SteffX Jan 25 '19 at 12:55
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    Probably easier for synthesis is to use a simpler starting material, more easily derived from feedstocks, e.g., https://pubs.acs.org/doi/abs/10.1021/jo00118a058 – Zhe Jan 25 '19 at 12:57
  • related https://chemistry.stackexchange.com/questions/42458/do-l-sugars-enantiomers-of-natural-sugars-have-a-sweet-taste – Mithoron Jan 25 '19 at 21:08

1 Answers1

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There is a nice review about synthesis of rare 6-carbon sugars.

They discuss two pathways to L-glucose. The first isomerizes L-fructose to L-glucose:

enter image description here

As you can see from the names of the enzymes, they have different natural substrates, but apparently, L-fructose and L-glucose fit into the active site as well. The reaction creates one additional stereocenter (on carbon 2), and the enzyme is stereospecific.

To make L-fructose, the enzyme L-rhamnulose-1-phosphate aldolase (RhaD) is used to catalyze the reaction of dihydroxyacetone and glyceraldehyde.

enter image description here

Fructose has three stereocenters while dihydroxyacetone is achiral and glyceraldehyde (with one stereocenter) may be used in racemic mixture. The enzyme selects the appropriate enantiomer of glyceraldehyde and is stereospecific in the creation of the new stereocenters (at carbons 3 and 4).

The other pathway starts with sorbitol, a so-called sugar alcohol (i.e. the carbonyl of the sugar has been reduced to a hydroxyl group). In the review cited above, the stereochemistry seems incorrect, and it would make sense to start with L-sorbitol (also known as D-gulitol or L-glucitol). The relationships between different rare (and common) sugars with respect to their stereochemistry is nicely illustrated in this review.

I did a search on Google Scholar, but to my surprise nothing came up.

Searching for "synthesis of L-glucose" brings up several papers. Search for "synthesis of rare sugars review " or "synthesis of rare hexoses review" yields the two references I cited (search done in 2022, not in 2019 when the question was asked).

Karsten
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