Asymmetric Anion Binding DMAP Catalysis in the Kinetic Resolution of Propargylic Amines

Significance

The Seidel group reports a kinetic resolution of a broad range of primary propargylic amines via an enantiodifferentiating acylation with benzoic anhydride. The reported catalyst system consists of the newly developed chiral thiourea-amide hydrogen-bonding catalyst 1 and DMAP as the nucleophilic catalyst. In the proposed mode of action the acylating reagent is activated by DMAP. The anion of the resulting ion pair binds to the chiral anion receptor 1 forming a chiral ion pair, which subsequently transfers an acyl group to the amine. The authors further demonstrate that this catalyst system is also suitable for benzylic amines, although the reported selectivities are somewhat lower than for propargylic substrates.