α-Diazo-β-ketonitriles: Uniquely Reactive Substrates for Arene and Alkene Cyclopropanation

An investigation of the intramolecular cyclopropanation reactions of α-diazo-β-ketonitriles is reported. These studies reveal that α-diazo-β-ketonitriles exhibit unique reactivity in their ability to undergo arene cyclopropanation reactions; other similar acceptor–acceptor-substituted diazo substrates instead produce mixtures of C–H insertion and dimerization products. α-Diazo-β-ketonitriles also undergo highly efficient intramolecular cyclopropanation of tri- and tetrasubstituted alkenes. In addition, the α-cyano-α-ketocyclopropane products are demonstrated to serve as substrates for S_(N)2, S_(N)2′, and aldehyde cycloaddition reactions