Synthesis of Spirotetrahydrofuran Oxindoles via Palladium-Catalyzed [4 + 1] Cycloaddition of Diphenyl 2-Oxoindolin-3-yl Phosphates and 2-Methylidenetrimethylene Carbonate

Abstract

A novel palladium-catalyzed [4 + 1] cycloaddition to give spirotetrahydrofuran oxindoles has been developed, in which diphenyl 2-oxoindolin-3-yl phosphates were used as the both electrophilic and nucleophilic C1 synthons at C-3 of the oxindole unit and 2-methylidenetrimethylene carbonate was used as the 1,4-dipole. The cycloannulation was performed at room temperature and provided the corresponding spirotetrahydrofuran oxindoles in good to excellent yields. The present method affords a new strategy for the construction of spirooxindole derivatives with unique three-dimensional structures.

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