In 2012, Byrne and Gilheany affirmed this reaction progresses differently in salt-containing and salt-free conditions, with the latter scenario being susceptible to “stereochemical drift.” (15[1])A [2+2] cycloaddition begins one of this reaction’s two mechanisms that sees the formation of a “closed” four-membered ring intermediate. One reagent is replaced with an ester carbanion in a variant of this reaction partly named (15[1])for Leopold (15[1])Horner. This reaction’s intermediate exists in an equilibrium between (*) betaine (“bay-tah-een”) and oxaphosphetane (“ock-sah-FOSS-fuh-tain”) forms. Phenyllithium (10[1])aids in the preferential formation of (E)-isomers in this reaction’s Schlosser modification. This is the most popular reaction used to convert a carbonyl into an alkene. A German chemist names, (-5[1])for 10 points, (-5[1])what reaction that makes use of triphenyl phosphonium ylide reagents? ■END■ (10[3]0[3])