An europium(III) complex as an efficient catalyst for the Michael reaction of α,β-enones with ketene silyl acetals: LIS-NMR analysis for the transition state through complexation between europium(III) catalyst and enones

Abstract

The europium(III) complex, Eu(dppm) 3, is found to be an efficient catalyst for the Michael reactions of α, β- enones with ketene silyl acetals. The high level of erythro selectivity obtained in the reaction of tert-butyl ( E)- propenyl ketones ( 2c) with (E)-1-tert-butoxy-1-[(trimethylsilyl)oxy]propene ( 3d) is rationalized on the basis of the LIS-NMR analysis of the europium(III) catalyst/enone 2c complex.