Highly selective syn glycolate aldol reactions with boron enolates of Masamune norephedrine esters

Boron enolates of norephedrine-based glycolate esters reacted with various aldehydes to produce syn aldol products in high yield and selectivity. The outcome is consistent with a Z enolate reacting through a closed transition state with reversal of the enolate facial selectivity relative to the propionate enolates.