Phase-transfer-catalyzed asymmetric S(N)Ar reaction of α-amino acid derivatives with arene chromium complexes.

Although phase-transfer-catalyzed asymmetric S(N)Ar reactions provide unique contribution to the catalytic asymmetric α-arylations of carbonyl compounds to produce biologically active α-aryl carbonyl compounds, the electrophiles were limited to arenes bearing strong electron-withdrawing groups, such as a nitro group. To overcome this limitation, we examined the asymmetric S(N)Ar reactions of α-amino acid derivatives with arene chromium complexes derived from fluoroarenes, including those containing electron-donating substituents. The arylation was efficiently promoted by binaphthyl-modified chiral phase-transfer catalysts to give the corresponding α,α-disubstituted α-amino acids containing various aromatic substituents with high enantioselectivities.