Diastereoselective synthesis of enantiopure γ-amino-β-hydroxy acids by Reformatsky reaction of chiral α-dibenzylamino aldehydes

N,N-Dibenzylamino aldehydes 1 react with Reformatskyʹs reagent leading to anti-γ-dibenzylamino-β-hydroxy esters 2 as the major stereoisomers. Treatment of 2 with TFA followed by hydrogenolysis on Pearlmanʹs catalyst yields the corresponding γ-amino-β-hydroxy acids 10. Contrarily, some N-butoxycarbonyl (Boc) amino aldehydes lead to syn-γ-tert-butoxycarbonylamino-β-hydroxy esters as the major product.