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

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-tetrachl orobicyclo[2.2.1]hept-5-en-2-endo-ol, obtained from the enzyme catalysed tr ansesterification of the racemate, was reduced and dechlorinated (Na/NH3; e thanol), followed by pyridinium chlorochromate oxidation of the resultant a lcohols to the corresponding ketones. After treatment with t-BuOK/BuONO, in a nitrosation reaction, alpha -keto oximes were obtained. Reduction over t wo steps with NaBH4 and NaBH4/NiCl2. 6H(2)O followed by in situ acetylation furnished the corresponding acetamido esters, which were hydrolysed with C H3OH/Na to produce the enantiopure amino alcohols in good yields. (C) 2001 Elsevier Science Ltd. All rights reserved.