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

Abstract

The first example of a Lewis acid catalysed asymmetric hydroxyamination of β-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 β-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).