Catalytic Asymmetric Aza-Cope Rearrangement

Significance

A catalytic asymmetric 2-aza-Cope rearrangement was achieved by ­Brønsted acid catalysis. The transformation is initiated by an in situ formation of the iminium ion 4 catalyzed by the chiral phosphoric acid 1. The resulting chiral ion pair undergoes a [3,3]-sigmatropic rearrangement to afford chiral imines 2 in good yield and er values of up to 97:3. The authors demonstrated that 2 could be derivatized to the free and protected homoallylic amines 5 and 6, respectively, in good yield and without any loss of enantiomeric excess.