The use of resident stereogenic centers to control the outcome of diastereoselective reactions is a powerful strategy for the construction of complex organic molecules. Although the influence of both α and β stereogenic centers on the addition of nucleophiles to aldehydes has been thoroughly studied, analogous studies of α-and β-substituted electron-deficient imines are sparse. We recently disclosed the first comprehensive study of α-alkoxy imines and demonstrated high levels of either syn or anti diastereoselectivity based on the nature of the nucleophilic alkene employed. That study also demonstrated that the typically mono-coordinate Lewis acid BF3•OEt2 can form a highly reactive chelate by disproportionation to BF2 + /BF4 -. Based on these observations, we sought to explore the factors influencing acyclic stereocontrol in β-alkoxy imines, allowing access to chiral 1,3 amino alcohols, a common motif in biologically active synthetic targets (Figure ). Previously reported examples of Lewis acid mediated nucleophilic additions of β-alkoxy aldehydes show how 1,3 asymmetric induction in β-alkoxy aldimines can result in highly selective reaction outcomes. Chelateable Lewis acids used in nucleophilic additions to β-alkoxy aldehydes lead to anti-2 in high diastereomeric ratios. Reetz 4 , Keck and Heathcock 7 rationalized this observed anti selectivity through the preferential approach of a nucleophile on the less hindered side of a six-membered chelate (Figure ). Evans later reported comparable anti selectivity in Mukaiyama aldol additions to βalkoxy aldehydes with BF3•OEt2, a typically non-chelating Lewis acid. Dipole minimization of the O-B bond of the monocoordinated Lewis acid/substrate complex and the O-C βalkoxy group were the proposed origin of the observed selectivity (Figure ).