Talk:Umpolung: Difference between revisions
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== Stereochemistry == |
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In Cyanide-type umpolung the OH should not show a stereochemistry (the product would be racemic). |
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In Carbonyl umpolung structures 6 & 12 show stereochemistry at a carbon that isn't chiral - the other C of the epoxide should show a configuration. |
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[[Special:Contributions/69.72.27.110|69.72.27.110]] ([[User talk:69.72.27.110|talk]]) 08:03, 31 October 2011 (UTC) |
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Revision as of 08:03, 31 October 2011
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Corey-Seebach Reaction
The dithiane umpolung is often referred to as the Corey-Seebach reaction; would anyone be against duplicating some of the content and extending it as part of a new article? — Preceding unsigned comment added by Mdlevin (talk • contribs) 02:43, 3 January 2011 (UTC)
Comments
Initial Comments: The article has a reasonable number of examples, but could use some more organization.
Suggestions:
- Have a global scheme that contrasts "normal" polarity reactions that result in 1,3- (aldol) and 1,5- (Michael) oxygenation with these "unnatural" polarity 1,2 (benzoin) and 1,4 (Stetter) reactions. It's mentioned in the text, but a graphic would be very useful.
- Showing carbenes as (+)(-) paired on a single, neutral center might be a useful way to show how they can invert polarity.
- The idea of alternating charges goes back a long way (Lapworth?) It might be useful to have a bit more discussion about the idea of alternating charges, and how newer methods override these natural tendencies.
- Some of the schemes are extremely crowded and "busy." Maybe break some of them up, add captions and labels, and stick to standard ACS settings and sizes.
- Phenolic coupling is an important reaction, and deserves some expanding on.
- Don't forget the Stetter reaction.
- I would put the NHC reactions together for organization. The scheme for the enone reaction shows 2a and 2b as resonance structures, but they are really tautomers.
Eugene Kwan (talk) 22:14, 24 October 2011 (UTC)
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Stereochemistry
In Cyanide-type umpolung the OH should not show a stereochemistry (the product would be racemic). In Carbonyl umpolung structures 6 & 12 show stereochemistry at a carbon that isn't chiral - the other C of the epoxide should show a configuration. 69.72.27.110 (talk) 08:03, 31 October 2011 (UTC)