Regio- and Diastereodivergent [4 + 2] Cycloadditions with Cyclic 2,4‑Dienones

By employing activated alkenes with bulky α-functional groups, such as α-cyano-α,β-unsaturated ketones and Meldrum’s acid–based alkenes, a previously unreported cross-trienamine pathway of cyclic 2,4-dienones is adopted to deliver γ′,δ-regioselective [4 + 2] cycloadducts catalyzed by cinchona-derived amines. In addition, a diastereodivergent [4 + 2] cycloaddition reaction is realized with Z-configured 4-alkylidene­isoxazol-5­(4H)-ones under similar catalytic conditions, even through a three- or four-component cascade process with simple starting materials.