Asymmetric construction of quaternary stereocenters by magnesium catalysed direct amination of β-ketoesters using in situ generated nitrosocarbonyl compounds as nitrogen sources

The first example of a Lewis acid catalysed asymmetric hydroxyamination of beta-ketoesters with nitrosocarbonyl compounds generated in situ was accomplished. The combination of a catalytic amount of Mg(OTf)(2) with a chiral N,N'-dioxide ligand provides highly substituted quaternary beta-keto amino acid derivatives in high yields (up to 97%) and enantioselectivities (up to 96%). Regioselectivities (N- vs. O-attack) are uniformly high for all substrates (>20 : 1).