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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. [ABSTRACT FROM AUTHOR]

A general [5+1] annulation reaction, which utilized 4-bromo- or 4-mesyloxy-but-2-enyl peroxides as unique five-atom bielectrophilic synthons to participate in the C–C and the subsequent umpolung C–O bond-forming reactions with C1 nucleophiles, has been developed for the facile synthesis of 2,2-disubstituted dihydropyrans in high yields under mild basic conditions. The dihydropyrans, which are readily prepared on a gram scale by this new method, can be flexibly transformed into the biologically important tetrahydropyrans and pyranones in 1–2 steps. [ABSTRACT FROM AUTHOR]