A nickel(0)-catalyzed intermolecular [3+2] cycloaddition of bis(alkylidenecyclopropanes) with diazenes such as diethyl or diisopropyl azodicarboxylate gave pyrazolidine-1,2-dicarboxylates in moderate to good yields (61–72%).
Keywords
bisalkylidenecyclopropanes - diazenes - pyrazolidinedicarboxylates - [3+2]-cycloaddition - nickel catalysis