Editing Ylide (section)

==Reactions==
An important ylide reaction is of course the [[Wittig reaction]] (for phosphorus) but there are more.

===Dipolar cycloadditions===
Some ylides are [[1,3-dipole]]s and interact in [[1,3-dipolar cycloaddition]]s. For instance an azomethine ylide is a dipole in the [[Prato reaction]] with [[fullerene]]s.

===Dehydrocoupling with silanes===
In the presence of the [[group 3 element|group 3]] [[homoleptic]] [[catalyst]] Y[N(SiMe<sub>3</sub>)<sub>2</sub>]<sub>3</sub>, triphenylphosphonium methylide can be coupled with [[phenylsilane]].<ref>{{cite journal |first1=Adi E. |last1=Nako |first2=Andrew J. P. |last2=White |first3=Mark R. |last3=Crimmin |title=A metal–amide dependent, catalytic C–H functionalisation of triphenylphosphonium methylide |journal=[[Chemical Science]] | year=2013 | volume=4 |issue=2 |pages=691–695 | doi=10.1039/C2SC21123H|hdl=10044/1/15254 |url=http://spiral.imperial.ac.uk/bitstream/10044/1/15254/2/Chemical%20Science_4_2_2013.pdf |hdl-access=free }}</ref> This reaction produces H<sub>2</sub> gas as a byproduct, and forms a silyl-stabilised ylide.

:[[Image:ChemSci TOC.png|400px|Yttrium catalysed dehydrocoupling of triphenylphosphonium methylide and phenylsilane]]

===Sigmatropic rearrangements===
Many ylides react in [[sigmatropic reaction]]s.<ref>{{cite journal |first1=J. B. |last1=Sweeney | title=Sigmatropic rearrangements of 'onium' ylides | journal=[[Chemical Society Reviews]] |year=2009 |volume=38 |issue=4 |pages=1027–1038 |doi=10.1039/b604828p |pmid=19421580}}</ref> The [[Sommelet-Hauser rearrangement]] is an example of a [2,3]-sigmatropic reaction. The [[Stevens rearrangement]] is a [1,2]-rearrangement.

A {{bracket|3,3}}-sigmatropic reaction has been observed in certain phosphonium ylides.<ref name=Ferguson>{{cite journal |last1=Ferguson |first1=Marcelle L. |last2=Senecal |first2=Todd D. |last3=Groendyke |first3=Todd M. |last4=Mapp |first4=Anna K. |year=2006 |title=<nowiki>[3,3]</nowiki>-Rearrangements of Phosphonium Ylides |journal=[[J. Am. Chem. Soc.]] |volume=128 |issue=14 |pages=4576–4577 |doi=10.1021/ja058746q |pmid=16594686}}</ref><ref>(i) Reaction of [[allyl alcohol]] with 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphorinane forms a [[phosphite ester]]. (ii) [[Metal carbene]] addition (from [[ethyl diazoacetate]] and [[ClFeTPP]]) forms an ylide. (iii) A rearrangement reaction (in blue) yields a [[phosphonate]].</ref>

:[[Image:Phosphoniumylide rearrangement.png|400px|Scheme 1. Phosphonium ylide rearrangement]]

===Allylic rearrangements===
Wittig reagents are found to react as nucleophiles in [[Allylic rearrangement|S<sub>N</sub>2' substitution]]:<ref>{{cite journal | title = Facile SN2' Coupling Reactions of Wittig Reagents with Dimethyl Bromomethylfumarate: Synthesis of Enes, Dienes, and Related Natural Products | first1=Ramesh M. |last1=Patel |first2=Narshinha P. |last2=Argade | journal = [[J. Org. Chem.]] | year = 2007 | volume = 72 | issue = 13 | pages = 4900–4904 | doi = 10.1021/jo070728z | pmid = 17539690}}</ref>

:[[Image:WittigAllylicrearrangement.png|400px|Wittig reagent in allylic rearrangement. 8% ene product not depicted]]

The initial addition reaction is followed by an [[elimination reaction]].