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.

Palladium(II) trifluoroacetate (5 mol %) catalyzes the C-arylation of N,N-disubstituted hydantoins by aryl iodides in good yield. The reaction proceeds through base-promoted enolization of the amino acid derived hydantoins, and the resulting 5,5-disubstituted hydantoins may be deprotected at one or both N atoms to yield biologically active structures or alternatively hydrolyzed to the parent α-aryl α-amino acids. The reaction is successful with a variety of parent amino acids and a range of electron-rich and electron-poor aryl iodides.

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.

A series of 1-aryl-3,4-dihydroisoquinolines (DHIQs) were synthesized and their barriers to bond rotation were determined by means of VT-NMR, dynamic HPLC or racemization studies. Although they all presented lower rotational stability than the related 1-arylisoquinolines (such as QUINAP), certain 1-aryl-DHIQ structures had a sufficiently high barrier to bond rotation to show axial chirality. These compounds included 1-(2-triflyl-1-naphthyl)-4,5dihydroisoquinoline 4h and 1-(2-diphenylphosphanyl-1-naphthyl)-4,5-dihydroisoquinoline 4i. This discovery opens the door to the development of a new group of axially chiral N,P ligands for asymmetric synthesis and also potentially to new strategies for the synthesis of axially chiral 1-arylisoquinolines. .

Pseudoephedrine-Directed Asymmetric -Arylation of -Amino Acid Derivatives. -Amino-acid-derived ureas (I) and (VI) are modified with pseudoephedrine as a chiral auxiliary to yield compounds (III) and (VII), which undergo LDA-promoted rearrangement including an aryl shift to yield hydantoins (IV) and (VIII). These hydantoins can be hydrolyzed to give chiral quaternary amino acids, e. g. compound (V). -(ATKINSON, R. C.; FERNANDEZ-NIETO, F.; MAS ROSELLO, J.; CLAYDEN*, J.; Angew. Chem., Int. Ed. 54 (2015) 31, 8961-8965, http://dx.doi.org/10.1002/anie.201502569 ; Sch. Chem., Univ. Manchester, Manchester M13 9PL, UK; Eng.) -Mais 49-127