The Wittig reaction is an organic reaction used to convert a primary or secondary alkyl halide and an aldehyde or ketone to an olefin using triphenylphosphine and base. Nα,Nα-Bis(carboxymethyl)-L-lysine structure The mechanism beings with attack of the PPH₃ on the alkyl halide which releases the halide anion and forms a phosphonium ion. The base then deprotonates at the alpha position to afford a phosphonium ylide. The ylide subsequently attacks the alde-hyde or ketone to form a zwitterion where the oxygen anion then attacks the phosphonium cation to form an oxaphosphetane. Fmoc-D-beta-indanylglycine In stock A rearrangement then generates the final olefin product and releases a triphenylphos-phine oxide by-product whose formation of a strong P=O bond is the driving force for this reaction. ^[1][2]