Direct α-amination of nitrones achieved by DBU-activated N-haloimides

Direct alpha-amination of nitrones has been developed by using N-haloimide-DBU protocol. Reaction of nitrones with N-haloimide takes place readily in the presence of DBU in DCM, affording directly alpha-aminonitrones in moderate to excellent yields. N-Haloimide activated by DBU provides both a halogen cation and a nitrogen anion source. E- and Z-isomerization of alpha-aminonitrones was examined and found to be highly sensitive to acidic substances like silica gel and Bronsted acid. In addition to nitrones, quinoline N-oxides are also suitable substrates. Direct amination achieved by the protocol demonstrates new reactivity of nitrones and quinoline N-oxides. (C) 2016 Elsevier Ltd. All rights reserved.