Rhodium-Catalyzed Asymmetric Allylation of Malononitriles as Masked Acyl Cyanide with Allenes: Efficient Access to β,γ-Unsaturated Carbonyls

Abstract

A rhodium-catalyzed regio- and enantioselective intermolecular allylation of malononitriles as masked acyl cyanides (MAC) with terminal and symmetrical internal allenes is reported. A Rh^I /Josiphos catalytic system combined with subsequent oxidative degradation of the primary adducts enables a straightforward access to α-branched, β,γ-unsaturated carbonyl compounds. The present protocol exhibits perfect atom economy in the allylation step and is characterized by a great functional group compatibility. Furthermore, the use of α-substituted malononitriles allowed for the construction of all-carbon quaternary centers.

Keywords: allylation; asymmetric catalysis; malononitrile; masked acyl cyanides; quaternary carbon centers.