Enantioselective Aza-Diels-Alder Reaction of Brassard’s Diene with Imines

Significance

The authors reported the first enantioselective aza-Diels-Alder reaction of Brassard’s diene 1 with aldimines 2 in the presence of chiral cyclic phosphate pyridinium salt 4 as Brønsted acid catalyst. A wide range of aromatic and aliphatic imines can react with Brassard’s diene 2 to afford α,β-unsaturated δ-lactams 3 with high yields and excellent enantioselectivities. This methodology was successfully applied on a one-gram scale without any loss in the yield or enantio­selectivity.