The betaine forms an oxygen-containing four-membered ring, which subsequently breaks up into the products.  
The Schlosser modification of this reaction uses excess lithium salts, which stabilize the intermediate betaine created in the first step.  The betaine forms an oxygen-containing four-membered ring, which subsequently breaks up into the products.  A similarly named modification of this reaction stabilizes one of the reactants, forming the E form of the desired product almost exclusively.  Named after the winner of the 1979 Nobel Prize in Chemistry, FTP, name this reaction, which forms an alkene from the reaction of a carbonyl group with a compound known as phosphorane or an ylide.
The Schlosser modification of this reaction uses excess lithium salts, which stabilize the intermediate betaine created in the first step.  
Wittig reaction