An efficient synthesis of enantiopure (+)- and (−)-3-exo-amino-7,7-dimethoxynorbornan-2-exo-ols
摘要:
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/NH3; ethanol), followed by pyridinium chlorochromate oxidation of the resultant alcohols to the corresponding ketones. After treatment with t-BuOK/BuONO, in a nitrosation reaction, alpha -keto oximes were obtained. Reduction over two steps with NaBH4 and NaBH4/NiCl2. 6H(2)O followed by in situ acetylation furnished the corresponding acetamido esters, which were hydrolysed with CH3OH/Na to produce the enantiopure amino alcohols in good yields. (C) 2001 Elsevier Science Ltd. All rights reserved.
An efficient synthesis of enantiopure (+)- and (−)-syn-1,3-amino alcohols with a norbornane framework and their application in the asymmetric addition of ZnEt2 to benzaldehyde
作者:Luciane F. de Oliveira、Valentim E.U. Costa
DOI:10.1016/j.tetasy.2004.07.027
日期:2004.8
A series of new optically active (+)- and (−)-syn-1,3-amino alcohols with a norbornane framework has been synthesized. Their abilities as chiral catalysts in the enantioselective additions of ZnEt2 to benzaldehyde were evaluated. High yields and enantiomeric excesses have been achieved (up to 91%). The influence of the configuration of the carbon bearing the hydroxyl group of the ligands has been studied
合成了具有降冰片烷骨架的一系列新的旋光性(+)-和(-)- syn -1,3-氨基醇。评估了它们在对苯甲醛中对映选择性添加ZnEt 2时作为手性催化剂的能力。已实现了高收率和对映体过量(高达91%)。已经研究了带有配体羟基的碳的构型的影响。对于观察到的对映选择性,也提出了合理的机制。