This reaction is the basis for a modification that uses electron-deficient reagents in a mixture of KHMDS and 18-crown-6. Semi-stabilized aryl reagents in this reaction do not achieve stereoselectivity, unlike stabilized (10[1])ester or unstabilized (10[1])alkyl reagents. Maryanoff and Reitz coined the term (10[1])“stereochemical (10[1])drift” (10[2])to describe the interconversion of betaine (10[1])intermediates in this reaction, (10[2])which can be controlled (10[1])using the Schlosser modification. (10[4])A modification of this reaction that uses carbanion reagents (10[1])to preferentially synthesize E products was proposed (10[1])by Leopold Horner. (10[2])In lithium-free (10[1])conditions, this reaction proceeds via a four-atom (10[1])oxaphosphetane intermediate. For 10 points, (10[1])name this reaction (10[1])that uses a triphenyl (10[2])phosphonium (10[6])ylide (10[2])(“ILL-id”) reagent (10[3])to convert (10[2])a carbonyl group into an alkene. ■END■ (10[4]0[25])