Favorskii-Type Rearrangement of α,α′-Dihalo Ketones with Sodiomalonates Leading to Conjugated Enone Derivatives

Abstract A new synthetic method of conjugated enones by the use of carbanion-induced Favorskii-type rearrangement is described. The reaction of α,α′-dihalo ketones R1R2(X)CC(O)CH2X with sodiomalonates Na+ −CR3(CO2R4)2 in THF at 0°C—room temperature gave conjugated enones R1R2C=CHC(O)CR3(CO2R4)2 in 42–66% yields. The reaction can be also adaptable to the enolates of ethyl cyanoacetate or malononitrile to give the corresponding enones.