Talk:Horner–Wadsworth–Emmons reaction

Beautiful

Some of these chemistry-related articles, especially on certain organ(-ic/-ometallic) reactions and reagents, are superb. I am really very impressed. Srnec 04:57, 19 March 2007 (UTC)[reply]

Wittig-Horner

When you search at that you are redirected to this page. But its not the same reaction as HWE, and btw I think you normally says Horner-Wittig (Google does) and there is no page... ChristianB 22:49, 10 July 2007 (UTC)[reply]

Question

"In contrast to phosphonium ylides used in the Wittig reaction, phosphonate-stabilized carbanions are more nucleophilic and more basic."

Is this true? Are they really more basic? How can that be? They are resonance stabilized, and the anion can be prepared by a relativly weak RO- type base. —Preceding unsigned comment added by 85.167.1.116 (talk) 10:26, 6 September 2007 (UTC)[reply]

I think the main reason is they are negatively charged, whereas a Wittig reagent is neutral. Also, the P=O bond is not a standard p-p pi bond, it is a d-p pi bond, which can't overlap (as C=P-O(-))in the same way that you would see in an enolate (C=C-O(-)). You need to compare like with like, so you need to compare the salt from (EtO)2P(=O)CH2CO2Et with Ph3P=CHCO2Et. Walkerma 13:58, 6 September 2007 (UTC)[reply]

Trisubstituted alkenes

I get confused by this section. It says "Aromatic aldehydes produce almost exclusively E-alkenes. " but the diagram right above it tells that aromatic aldehydes can produce predominantly either E or Z alkenes depending on the substituents of the phosphonate ester. Which one is right or am I misinterpreting this? --Choij (talk) 13:12, 23 December 2008 (UTC)[reply]

Electron movement in 4a and 4b.

In general, the arrows depicting the cleavage of the phosphonate and oxygen would be reversed. As a highly electronegative atom, oxygen would not be expected to relinquish one of its electrons and acquire one from somewhere else in the molecule as shown. The usual accepted mechanism for a Witting type reaction is that the electrons from the phosphorus-carbon bond are those that form the alkene, and the oxygen forms a pi bond with the phosphorus, which is resonance stabilized with the negatively charged oxygen bonded to the phosphorus. Both oxygen atoms on the phosphonate would then be stabilized by some counterion. — Preceding unsigned comment added by KE0GZW (talk • contribs) 16:08, 22 December 2015 (UTC)[reply]