Asymmetric (4+3) and (4+1) Annulations of Isatin-derived Morita-Baylis-Hillman Carbonates to Construct Diverse Chiral Heterocyclic Frameworks

A chiral tertiary amine-catalyzed asymmetric gamma-regioselective (4 + 3) annulation reaction of isatin-derived Morita-Baylis-Hillman carbonates and 1-azadienes was developed, delivering chiral azepane spirooxindoles with excellent stereoselectivity. In addition, by tuning the substituents of Morita-Baylis-Hillman carbonates, the switchable gamma-(4 + 3) or alpha-(4 + 1) annulation reaction with o-quinone methides was observed to furnish benzo[b]oxepines or 2,3-dihydrobenzofurans, respectively, under similar catalytic conditions.