The Perkow reaction is also used in the synthesis of novel quinolines. When the substituent is n-butyl the reaction product is the classical Perkow adduct. In this reaction the leaving group is an electron deficient acyl group (owing to the presence of three fluorine groups). When the substituent on the other hand is phenyl (not shown) the phosphite has a preference for reaction with the acyl group leading to an ethyl enol ether. Key in explaining the difference in reactivity is the electron density on the α-keto carbon atom.