Synthesis of enaminoketones using imidoylbenzotriazoles and silyl enol ethers

ORGN 48

Amy E. Hayden and Kostyantyn Kirichenko. Department of Chemistry, Center for Heterocyclic Compounds, University of Florida, PO Box 117200, Gainesville, FL 32611-7200
Several enaminoketones were synthesized from imidoylbenzotriazoles and silyl enol ethers. Imidoylbenzotriazoles serve as important alternatives to imidoyl chlorides due to their enhanced stability. Imidoylbenzotriazoles can be synthesized from amides using 1-chloro-1H-benzotriazole and triphenylphosphine. In the reaction to synthesize enaminoketones, unwanted self-aldol condensation was curtailed by the use of silyl enol ethers in place of ketones, preventing hydrolysis of the imidoylbenzotriazoles. Target enaminoketones were synthesized using base-assisted nucleophilic substitution of imidoylbenzotriazoles by silyl enol ethers. Yields of 50 – 80 % were accomplished with this novel synthetic strategy.