A convenient synthesis of piperidine-based β-amino alcohols from l-Phe and highly enantioselective addition of diethyl zinc to aldehydes

Abstract

β-Amino alcohols 4a– e were easily prepared from l-phenylalanine in three simple straightforward steps. The key intermediate compound ( S)- 3 was achieved in high yield (up to 92%) with glutaraldehyde and NaBH 4/H 2SO 4 in THF at room temperature. These five ligands were applied to catalyze enantioselective addition of diethyl zinc to aldehydes, high asymmetric induction was observed with 4c and 4e, and the ee value was up to 98%. The effect of the substitutes on the nitrogen atom was also observed via comparing piperidine-based amino alcohols with pyrrolidine-based similar ligands.