The selective reduction of protected amino ketone derivatives is preferred because of their good stability. [ 8 8. Fujisawa , T. ; Hayashi , H. ; Kishioka , Y. Enantioselective synthesis of optically pure amino alcohol derivatives by yeast reduction . Chem. Lett. 1987 , 129 – 132 . [CrossRef], [Web of Science ®] View all references ] However, their precursors (amino ketones) are difficult to isolate as free amines because of the formation of Schiff bases. ...