Asymmetric Synthesis of Substituted anti-β-Fluorophenylalanines.

A range of substituted anti-β-fluorophenylalanines was produced from the corresponding enantiopure α-hydroxy-β-amino esters using a stereospecific XtalFluor-E promoted rearrangement procedure as the key step. The requisite substrates are readily produced via aminohydroxylation of an α,β-unsaturated ester using our lithium amide conjugate addition methodology and, following rearrangement, deprotection of the resultant enantiopure β-fluoro-α-amino esters gives the corresponding enantiopure anti-β-fluorophenylalanines in good yield and high diastereoisomeric purity.