Diastereodivergent synthesis of fully disubstituted spiro[indoline-3,2’-pyrrolidin]-2-ones via tuneable Lewis base/Brønsted base-promoted(3+2)cycloadditions

Herein we report a diastereodivergent synthesis of fully disubstituted spiro[indoline-3,2’-pyrrolidin]-2-ones through base-promoted(3+2)cycloadditions.Importantly,the catalysts are found to have full control over the configuration of the stereocenters.When a Lewis base(PCy3)is used as a catalyst,good yields and excellent diastereoselectivities are obtained,regardless of the properties of the substituents,whereas spiro[indoline-3,2’-pyrrolidin]-2-ones of a different diastereoisomer are produced in good yields when a Brønsted base(K_(2)CO_(3))is used.ESI-MS experiments proved the existence of key zwitterionic intermediates.