Diene-transmissive hetero-Diels–Alder sequences involving carbonyl dienophiles are reported for the first time. High enantioselectivities are achieved in the reaction of phenylglyoxal with a broad range of dendralene structures, through the optimization of a Pd2+ catalyst system. The initial catalyst-controlled enantioselective oxa-Diels–Alder (ODA) cycloaddition to a dendralene generates a dihydropyran carrying a semicyclic diene. This participates in a subsequent catalyst or substrate-controlled Diels–Alder reaction to generate sp3-rich fused polycyclic systems containing both heterocycles and carbocycles. Computational investigations reveal a concerted asynchronous mechanism. π-Complexation of a diene C=C bond to Pd2+ occurs in both the pre-transition state (TS) complex and in cycloaddition TSs, controlling stereoselectivity. A formal enantioselective [4+2]cycloaddition of a CO2 dienophile is demonstrated.
|Number of pages||6|
|Journal||Angewandte Chemie - International Edition|
|Early online date||28 Jul 2022|
|Publication status||Published - 26 Sept 2022|
- Asymmetric Catalysis
- Domino Reactions