Talk:Diels-Alder reaction
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[edit] ortho, meta, para:
Are these descriptors only used for aromatic systems? But I would not know the right description by myself... Maybe 3,4-disubstituted cyclohexene? The 3,4-disubstituted cyclohexene is favoured over the 3,5-disubstituted cyclohexene...
- In my experience, one describes the relative positioning of the EWG and EDG substituents relative to each other ("the 1,2-product or 1,4-product is favored, the 1,3-product is not usually formed"). One is concerned with the reaction itself, not the product as a whole. There could be more than one olefin in the product. DMacks 15:15, 8 May 2006 (UTC)
[edit] niobium pentachloride
Is niobium pentachloride really the best example of a catalyst? Wouldn't something more common be appropriate?
- What do you mean with appropriate? niobium pentachloride is just one of many catalysts reported in the literature. So please feel free to add any catalysts you wish to include, when possible with a citation.
V8rik 17:59, 26 January 2006 (UTC)
It's just when I go to do an organic reaction with a Lewis acid, NbCl5 just isn't the first to come to mind; I would have to look up a more common Lewis acid.
- AlCl3
[edit] Electronic stability of s-trans
I removed the sentence The reason for this is that trans conformation allows the electrons from each double bond to very slightly overlap and lower the overall molecular orbital of butadiene. from the section "The diene". The intended topic is probably conjugation, which should be stated if so. But s-cis dienes are also conjugated, so the statement does not support s-trans being prefered. DMacks 03:18, 23 February 2006 (UTC)
[edit] Reverse?
Can this reaction go in the reverse?
- Ayup...this fact is mentioned in the third sentence of the introductory paragraph. DMacks 01:01, 12 October 2006 (UTC)
[edit] Predicting sterochemistry
It is not true for the endo transition state that the substituents on dienophile and 1,4-substituents on diene will always point towards the same side of the newly formed ring...In the picture below, it just happens that the endo transition state will yield substituents on same side of the ring.
can be very unclear to someone who does not realize that Cp is one of the few, if not only dienes with bulky substituents naturally in the inner position. I favor stating the rules which say
"out-endo-cis" (corollary "out-exo-trans")
"in-exo-cis"
where "out" or "in" refer to the position of a diene substituent, "endo" or "exo" refer to the orientation of the dienophile substituent, and "cis" or "trans" refer to the stereochemistry of the two substituents in question.
Thoughts?
