Trichloroacetimidic esters of 2,3-epoxy alcohols are transformed into oxazolines 5 and dihydrooxazines 6, respectively, depending on the structure of the educts and the catalyst. The five-membered ring compounds 5 are transformed into erythro-α-amino-β-hydroxy acids (60-70% from epoxy alcohols) via oxazolidinones 11, 12, and 13. α-Amino acids and α-substituted α-amino acids 10 as well as the corresponding aldehydes 9 are obtained from the dihydrooxazines 6 (50-60% from epoxy alcohols).