A Unified Catalytic Asymmetric (4+1) and (5+1) Annulation Strategy to Access Chiral Spirooxindole‐Fused Oxacycles

Abstract A unified catalytic asymmetric ( N +1) ( N =4, 5) annulation reaction of oxindoles with bifunctional peroxides has been achieved in the presence of a chiral phase‐transfer catalyst (PTC). This general strategy utilizes peroxides as unique bielectrophilic four‐ or five‐atom synthons to participate in the C−C and the subsequent umpolung C−O bond‐forming reactions with one‐carbon unit nucleophiles, thus providing a distinct method to access the valuable chiral spirooxindole‐tetrahydrofurans and ‐tetrahydropyrans with good yields and high enantioselectivities under mild conditions. DFT calculations were performed to rationalize the origin of high enantioselectivity. The gram‐scale syntheses and synthetic utility of the resultant products were also demonstrated.