Insight into Diastereoselective Synthesis of β-Furan/Pyrrole-Substituted Cyclohexenone Derivatives through AlCl-Catalyzed Cascade Rearrangement of Diels-Alder Cycloaddition Intermediates.

Herein, a strategy for the diastereoselective formal conjugate addition of heteroarenes and cyclic enone derivatives via the promotion of aluminum catalyst under mild conditions was reported. The formal Michael addition of a range of heteroarene dienes, including furans and pyrroles, to a variety of cyclohexanedienone derivatives containing a natural product and drug substrate occurred to achieve corresponding β-furan/pyrrole substituted cyclohexenone products up to 99% yield. Control experiments and DFT calculations revealed that the novel reaction mechanism involved an initial ligand exchange, followed by a cascade reaction of Diels-Alder cycloaddition, C-C bond cleavage, intramolecular [1,5]-H migration, and enol-keto tautomerism processes.