Pseudoephedrine-Directed Asymmetric α-Arylation of α-Amino Acid Derivatives
Available α-amino acids undergo arylation at their α position in an enantioselective manner on treatment with base of N′-aryl urea derivatives ligated to pseudoephedrine as a chiral auxiliary. In situ silylation and enolization induces diastereoselective migration of the N′-aryl group to the α 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.
Atkinson, Rachel C.,Fernández-Nieto, Fernando,Mas Rosell?, Josep,Clayden, Jonathan
supporting information
p. 8961 - 8965
(2015/08/03)
Intramolecular arylation of amino acid enolates
Dianionic enolates formed from N′-aryl urea derivatives of amino acids undergo intramolecular C-arylation by attack of the enolate anion on the N′-aryl ring, leading to a hydantoin derivative of a quaternary amino acid. In situ IR studies allow identification of four intermediates on the reaction pathway.
Atkinson, Rachel C.,Leonard, Daniel J.,Maury, Julien,Castagnolo, Daniele,Volz, Nicole,Clayden, Jonathan
supporting information
p. 9734 - 9736
(2013/10/21)
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