Favoring Trienamine Activation through Unconjugated Dienals: Organocatalytic Enantioselective Remote Functionalization of Alkenes

Unconjugated 2,5‐dienals are more reactive substrates than the corresponding fully conjugated α,β,γ,δ‐unsaturated aldehydes towards organocatalytic activation through trienamine intermediates. This difference in reactivity has been demonstrated in the Diels–Alder reaction with nitroalkenes, a reaction that proceeds with clean β,ε‐selectivity to afford the final products in high yields and stereoselectivities, the related polyconjugated 2,4‐dienals being completely unreactive.