A highly diastereo- and enantioselective hetero-Diels–Alder (HDA) reaction of a Brassard-type diene with aliphatic aldehydes has been developed. The chiral N,N′-dioxide L2/In(OTf)3 complex was efficient toward the obtention of the corresponding β-methoxy-γ-methyl α,β-unsaturated δ-lactones in good yields (up to 86%) as well as dr and ee values (up to 97:3 cis/trans and 94% ee). In addition, the product