The Influence of a β-Electron Withdrawing Substituent in Aldol Reactions of Methylketone Boron Enolates.

We wish to describe here that good levels of substrate-based, 1,5-syn-stereocontrol could be achieved in the boron-mediated aldol reactions of β-trichloromethyl methylketones with achiral aldehydes, independent of the nature of the β-alkoxy protecting group.