Expedient asymmetric synthesis of (2S,3S)-Boc-phenylalanine epoxide, a key intermediate for the synthesis of biologically active compounds

Abstract The asymmetric synthesis of (2 S ,3 S )-3-( tert -butoxycarbonyl)amino-1,2-epoxy-4-phenylbutane [(2 S ,3 S )-Boc-phenylalanine epoxide] has been achieved in six steps and in 55% overall yield from the N- benzylimine derived from ( R )-2,3- O -isopropylidene-glyceraldehyde. The required vic -aminodiol intermediate was obtained through a highly diastereoselective addition of benzylmagnesium chloride to the N -benzylimine in the presence of BF 3 ·OEt 2 as an imine precomplexing agent.