Task: Text Categorization
Input (English): One reactant for this reaction is best prepared by an S N 2 nucleophilic addition of a triphenyl compound, followed by elimination of the hydrogen halide by an organolithium reagent. This reaction itself proceeds through a rather unique intermediate formed when the pi electron from the reagents carbon-oxygen double bond migrates to the positively charged pole of one reactant; this intermediate is called a an oxaphosphetane, from which a triphenyl oxide is eliminated to complete the reaction. The aforementioned positively charged pole is on phosphorous because the aforementioned prepared reactant is a phosphorous ylide. For ten points, name this reaction that produces selectively double-bonded alkenes from aldehydes and phosphorous ylides and that is named for the German 1979 Chemistry Nobel winner.
Output (English): Science