Scheme 5. One-Pot Two-Step Stereoselective Synthesis of γ-Hydroxy-α-amino Acids 6, Using Benzylamine (7) as an Amine Donor for the Enzymatic Transamination Reaction and BAL to Transform the Benzaldehyde Formed (8) into Benzoin (9).
Dotted lines indicate a transamination reaction of the aldehydes 1 and pyruvate 2, favoring the retroaldolysis of 3 catalyzed by the HBPA present in the system.