Magnesium bis(diisopropylamide), a useful reagent for regio- and stereoselective synthesis of kinetic silyl enol ethers

Article abstract of DOI:10.1016/S0040-4039(99)00665-6

Less highly substituted silyl enol ethers are regiospecifically prepared in high yield, around room temperature under kinetic conditions, from unsymmetrical cyclic ketones and magnesium bis(diisopropylamide) [(DA)₂Mg] in THF/heptane. This high regioselectivity is markedly higher than these reported for bromomagnesium diisopropylamide (DAMgBr); it is also similar to this of LDA/DME at -78°C, but (DA)₂Mg can be used at room temperature. In addition, a high E-enolization stereoselectivity is observed for benzylic ketones, reverse of this obtained with LDA.