Glycolate aldol reactions with boron enolates of bis-4-methoxyphenyl dioxanone

The boron enolate of 5S,6S-bis-5,6-(4-methoxyphenyl)-2-dioxanone reacted with various aldehydes to produce anti glycolate aldol products in high yield with good selectivity. The outcome is consistent with an E-enolate reacting through a closed transition state. The adducts were protected and the auxiliary was conveniently removed with ceric ammonium nitrate to give useful intermediates.