Editing Ylide (section)

===Based on oxygen===
'''Carbonyl ylides''' (RR'C=O<sup>+</sup>C<sup>−</sup>RR') can form by ring-opening of [[epoxide]]s or by reaction of [[carbonyls]] with electrophilic [[carbenes]],<ref>{{cite journal |first1=Albert |last1=Padwa |title=Catalytic Decomposition of Diazo Compounds as a Method for Generating Carbonyl-Ylide Dipoles |journal=[[Helvetica Chimica Acta]] |year=2005 |volume=88 |issue=6 |pages=1357–1374 |doi=10.1002/hlca.200590109}}</ref> which are usually prepared from [[diazo]] compounds. '''Oxonium ylides''' (RR'-O<sup>+</sup>-C<sup>−</sup>R'R) are formed by the reaction of [[ethers]] with electrophilic [[carbenes]].