Comments on: A Request for a Crowdsourced Investigation of Digitonin

By: Markus Sitzmann

Markus Sitzmann — Mon, 10 May 2010 15:23:29 +0000

Well, as I can see, ChemSpider shows now a specific structure for Digitonin. I would say, let’s go with it – however, a cool feature in ChemSpider would be if the Digitonin page would indicate that there was a discussion about this structure (even cooler would be if the entire discussion could be recallable – unfortunately, it went out in so many places).

And regrettably, I can not help with NMR work … my knowledge about NMR is old an rusty … and that is probably a flattering way to describe it

By: Antony Williams, ChemSpiderman

Antony Williams, ChemSpiderman — Thu, 06 May 2010 17:20:17 +0000

Markus….where we have ended up, as far as I can tell based on everything I have followed…is we have a set of extracted assertions/opinions about what the structure might be. I am stuck as to what the final structure of digitonin is actually. I know you’ve followed this discussion quite closely. What’s your opinion? Do you feel we have an answer as a result of all the work that has been done? If not it may well be worth doing the work to figure it out. That would mean some NMR work and I am always up for that

By: Markus Sitzmann

Markus Sitzmann — Wed, 05 May 2010 21:49:12 +0000

What is the final status of Digitonin?

By: Kirill

Kirill — Wed, 24 Feb 2010 23:04:04 +0000

Does not look like that

By: Egon Willighagen

Egon Willighagen — Tue, 09 Feb 2010 12:54:13 +0000

ChemSpiderMan: did this exercise result in a common agreement? What’s the link to the correct ChemSpider entry?

By: Markus Sitzmann

Markus Sitzmann — Mon, 21 Sep 2009 15:58:59 +0000

Interesting, the Wikipedia structure of Digitonin which lacks the definition of a stereo center (as I mentioned above) appeared only recently on Wikipedia (the change appeared Sept. 6; before that date a better structure was shown).

By: Markus Sitzmann

Markus Sitzmann — Thu, 17 Sep 2009 20:52:46 +0000

Some comment to my comment.gif graphic above: forget the blue part – this was a mistake by me (changing the flat tire at my wife’s minivan in the rain just gave me enough fresh air to finally see my error )

Besides that, I agree with all the things Mat Todd posted in his blog. The original structure (which I called Muhr structure) seems to be identical to the “Magnetic Resonance in Chemistry 1996″ structure posted by Mat, however – as Mat writes – this structure is not identical to the commonchemistry structure.

Here is my corrected form of this structure as SDF

http://cactus.nci.nih.gov/download/muhr_corrected.sdf

Std.InChIKey of this structure is InCHIKey=UVYVLBIGDKGWPX-DXBRUFHKSA-N

By: Kirill Degtyarenko

Kirill Degtyarenko — Thu, 17 Sep 2009 19:55:06 +0000

I think that the paper “The Constitution and Stereochemistry of Digitogenin” http://dx.doi.org/10.1021/ja01594a052 should be a concise version of the dissertation I mentioned in the previous post .

Digitogenin (structure Ia on page 3169) is drawn with methyl at C-20 going DOWN and hydrogen going UP (convention here is, solid line = UP, dashed line = DOWN). Unexplicably, when I is transformed into structure XI or XIII, the same methyl group is pointing UP.

I find nothing in the body of the article but the footnote (9) goes like this:
(9) Gitogenin and tigogenin have been interrelated via gitogenic acid (III) as well as through Δ2-22a,25a,5α-spirosten (VIII) (see ref.
24). Since tigogenin can be obtained from diosgenin (cf. R. E. Marker, T. Tsukamoto and D L. Turner, THIS JOURNAL, 62, 2525 (1940)), all of the arguments pertaining to the configuration at C-20 and C-22 of diosgenin (for leading references see H. Hirschmann, F. B. Hirschmann and J. W. Corcoran, J. Org. Chem., 20, 572 (1955) http://dx.doi.org/10.1021/jo01123a004 , and M. E. Wall, Experientia, 11, 340 (1955)
http://dx.doi.org/10.1007/BF02159909 ) also apply to digitogenin. V. H. T. James (Chemistry & Industry, 1388 (1953)) has related the configuration of C-25 in diosgenin with D-glyceraldehyde.

I am not sure that “leading references” will lead us to any direct evidence of configuration of digitogenin at C-20 but still I think we should check them out.

By: Markus Sitzmann

Markus Sitzmann — Thu, 17 Sep 2009 16:20:43 +0000

Nice article, Mat!

However, from your article I saw that the Wikipedia structure lacks a stereo center compared to commonchemistry

http://cactus.nci.nih.gov/download/wiki_common.gif

By: Kirill Degtyarenko

Kirill Degtyarenko — Thu, 17 Sep 2009 13:11:52 +0000

I wonder if anybody can get hold of the following dissertation:
The structure and stereochemistry of digitogenin. (1956)

See: http://en.scientificcommons.org/3963319