One-pot enol silane formation-Mukaiyama aldol reactions: Crossed aldehyde-aldehyde coupling, thioester substrates, and reactions in ester solvents
作者:C. Wade Downey、Grant J. Dixon、Jared A. Ingersoll、Claire N. Fuller、Kenneth W. MacCormac、Anna Takashima、Rohina Sediqui
DOI:10.1016/j.tetlet.2019.151192
日期:2019.10
Trimethylsilyl trifluoromethanesulfonate (TMSOTf) and a trialkylamine base promote both in situ enol silane/silyl ketene acetal formation and Mukaiyama aldol addition reactionsbetween a variety of reaction partners in a single reaction flask. Isolation of the required enol silane or silyl ketene acetal is not necessary. For example, crossed aldolreactionsbetween α-disubstituted aldehydes and non-enolizable
The Mukaiyama aldol reaction of silyl ketene acetals with aldehydes has been effected by using commercially available 4 angstrom molecular sieves (4 angstrom MS) as a promoter. Various silyl ketene acetals and silyl enol ethers have been shown to be effective nucleophiles for this reaction. For the first time, it has been found that 4 angstrom MS can promote the Mukaiyama Michael addition reactions of silyl ketene acetals to alpha,beta-enones.
Quaternary ammonium enolates as synthetic intermediates. Generation of ester enolates by the aid of α-trimethylsilylesters and quaternary ammonium fluoride, and their reactions with carbonyl compounds