Pseudoephedrine-Directed Asymmetric -Arylation of -Amino Acid Derivatives

Available -amino acids undergo arylation at their position in an enantioselective manner on treatment with base of N-aryl urea derivatives ligated to pseudoephedrine as a chiral auxiliary. Insitu silylation and enolization induces diastereoselective migration of the N-aryl group to the position of the amino acid, followed by ring closure to a hydantoin with concomitant explulsion of the recyclable auxiliary. The hydrolysis of the hydantoin products provides derivatives of quaternary amino acids. The arylation avoids the use of heavy-metal additives, and is successful with a range of amino acids and with aryl rings of varying electronic character.