An efficient synthesis of enantiopure (+)- and (−)-3- exo-amino-7,7-dimethoxynorbornan-2- exo-ols

Abstract

We describe the synthesis of new amino alcohols (+)- and (−)-3- exo-amino-7,7-dimethoxynorbonan-2- exo-ols. The (+)- or (−)-7,7-dimethoxy-1,4,5,6-tetrachlorobicyclo[2.2.1]hept-5-en-2- endo-ol, obtained from the enzyme catalysed transesterification of the racemate, was reduced and dechlorinated (Na/NH 3; ethanol), followed by pyridinium chlorochromate oxidation of the resultant alcohols to the corresponding ketones. After treatment with t-BuOK/BuONO, in a nitrosation reaction, α-keto oximes were obtained. Reduction over two steps with NaBH 4 and NaBH 4/NiCl 2·6H 2O followed by in situ acetylation furnished the corresponding acetamido esters, which were hydrolysed with CH 3OH/Na to produce the enantiopure amino alcohols in good yields.