Asymmetric Diels–Alder Cycloaddition of 1-Aminocyclohexadiene to Chiral Acrylate: Synthesis of Enantiopure Bridgehead-Aminobicyclo[2.2.2]octane-2-carboxylic Acid Derivatives
作者:Olivier Songis、Claude Didierjean、Camille Laurent、Jean Martinez、Monique Calmès
DOI:10.1002/ejoc.200700236
日期:2007.7
2R,4R)-1-(benzyloxycarbonylamino)bicyclo[2.2.2]oct-5-ene-2-carboxylic acid [(1S,2R,4R)-4], (1R,2R,4S)-1-(benzyloxycarbonylamino)bicyclo[2.2.2]oct-5-ene-2-carboxylic acid [(1R,2R,4S)-5] and (R)-1-aminobicyclo[2.2.2]octane-2-carboxylic acid [(R)-6]. This work has led to the preparation of these enantiopure bicyclic β-amino acids and provides a rare example of an asymmetric Diels–Alder reaction by microwave
(R)-4-(3-羟基-4,4-二甲基-2-氧代吡咯烷-1-基)苯甲酸苄酯(R)-2的丙烯酸酯衍生物与1-(苄氧羰基氨基)环己二烯3在微波下反应在无溶剂条件下进行辐照,以良好的产率 (91%) 产生 [4+2] 环加合物。反应以中等内向选择性 (67%) 和良好的面部选择性 (90%) 进行。分离并转化主要的环加合物以提供三种对映体纯双环 β-氨基酸:(1S,2R,4R)-1-(苄氧羰基氨基)双环[2.2.2]oct-5-ene-2-羧酸[(1S, 2R,4R)-4], (1R,2R,4S)-1-(benzyloxycarbonylamino)bicyclo[2.2.2]oct-5-ene-2-羧酸 [(1R,2R,4S)-5] 和 ( R)-1-氨基双环[2.2.2]辛烷-2-羧酸[(R)-6]。这项工作导致了这些对映体纯双环 β-氨基酸的制备,并提供了通过微波活化进行不对称 Diels-Alder