2-Nitromethylacrylates as Useful Dinucleophiles for the Enantioselective Organocatalytic Michael/Henry Cascade Reaction

2-Nitromethylacrylates have proved to be suitable 1,3-dinucleophiles reacting with α,β-unsaturated aldehydes in the presence of a secondary-amine catalyst to furnish Michael/Henry cascade products in moderate yields and with high enantioselectivities although with moderate diastereoselectivities. The reaction proceeds by iminium ion activation of the enal, which reacts regioselectively with the γ-carbon of the nitronate anion formed in situ, furnishing the desired cyclohexenes with three new stereocenters. Furthermore, and trying to avoid the diastereoselectivity issue, an efficient sequential Michael/Henry/dehydration reaction has been developed leading to enantiopure cyclohexadienes in moderate yields and excellent enantioselectivities.