Chemo-enzymatic synthesis of the active enantiomer of the anorressant 2-benzylmorpholine

Baker's yeast reduction of (Z)-alpha-bromocinnamaldehyde 1 in the presence of absorbing resins allows the easy preparation of the corresponding satura ted bromo-alcohol 2 in high yields and enantiomeric excess. The absolute co nfiguration is assigned through conversion into the (R)-phenyl oxirane 3 an d 1-phenyl-2-propanol 4 of (S) absolute configuration. The (R)-epoxide is t ransformed into 6, the pharmacologically active enantiomer of the appetite suppressant 2-benzylmorpholine, to which the (R) configuration is assigned. (C) 1998 Elsevier Science Ltd. All rights reserved.