Single enantiomer cyclopropylalanine (> 99.9% ee) and various derivatives were prepared using an asymmetric hydrogenation approach with a rhodium catalyst based on the methyl BoPhoz™ ligand. N-Boc cyclopropylalanine benzyl ester was the preferred derivative, as this material is ripe for further selective reaction and can be recrystallized to> 99.5% enantiomeric excess.
