Text this: Alkene synthesis using phosphonium ylides as umpolung reagents

             ___                 ___      ______  
    ___     / _ \\      ___     / _ \\   /_   _// 
   /   ||  / //\ \\    /   ||  / //\ \\    | ||   
  | [] || |  ___  ||  | [] || |  ___  ||  _| ||   
   \__ || |_||  |_||   \__ || |_||  |_|| /__//    
    -|_|| `-`   `-`     -|_|| `-`   `-`  `--`     
     `-`                 `-`