The Wadsworth-Emmons-Horner reaction is a commonly used variant of this reaction.  
The Wadsworth-Emmons-Horner reaction is a commonly used variant of this reaction.  Two intermediates are produced during it: a dipolar charge-separated species called a betaine [BAY-tuh-een] and a four-membered heterocycle that breaks down to give the final products.  It uses a phosphonate carbanion, but it can be conducted using sulfur ylides, though epoxides result.  FTP, name this reaction between a phosphorus ylide [ILL-ide] and a carbonyl, which won its namesake the 1979 Nobel in chemistry.
The Wadsworth-Emmons-Horner reaction is a commonly used variant of this reaction.  
Wittig reaction