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Synthesis of Spirocyclopropane Oxindoles via Michael-Initiated Cyclopropanation of Pyridinium Salts with 3-Ylidene Oxindoles

A Michael-initiated ring closure reaction of pyridinium salts with arylidene oxindoles has been developed. A wide range of aryl substituted spriocyclopropane oxindoles have been achieved in moderate to good yields (41–99%). This efficient strategy exhibits good functional group compatibility and may serve as an attractive method for the synthesis of diverse cyclopropanes.