DIASTEREOSELECTIVE CONVERSION OF L-(S)-ERYTHRULOSE TO 2-AMINO-2-DEOXY-1-ERYTHRITOL

摘要

L-(S)-Erythrulose (1) was converted into 2-amino-2-deoxy-L-erythritol (2) (six steps, overall yield 35%) through diastereoselective reduction of the bridged orthoester 21, (1S,5S)-2,7,8-trioxabicyclo[3.2.l]octan-4-one-O-benzyloxime, with K-selectride(R) as the key process. Alternative methods, involving reduction of the imino group in acyclic O-benzyloxime derivatives of 1, or reductive amination of the 2-ketone function, afforded various proportions of erythro and threo 2-amino diastereoisomers. The distribution of rotamers for the deprotected ammonium salts apparently is governed by hydrogen bonding between the ammonium group and the 3-hydroxyl oxygen, resulting in characteristic (3)J(H-2,H-3) coupling constant values. Substitution of the bridged O-benzyloximes 21 and 22 via deprotonation of the alpha-methylene position was not successful. [References: 28]