Rearrangement of an Intermediate Cyclopropyl Ketene in a Rh^II-Catalyzed Formal [4 + 1]-Cycloaddition Employing Vinyl Ketenes as 1,4-Dipoles and Donor–Acceptor Metallocarbenes

Abstract

-catalyzed formal [4 + 1]-cycloaddition approach toward spirooxindole cyclopentenones is described. The diastereoselective cyclopropanation of vinyl ketenes with diazooxindoles as C1 synthons initiated a relatively mild formal [1,3]-migration of an intermediate cyclopropyl ketene to provide spirooxindoles in good to excellent yields (36-99%).