The use of (−)-8-phenylisoneomenthol and (−)-8-phenylmenthol in the enantioselective synthesis of 3-functionalized 2-azabicyclo[2.2.1]heptane derivatives via aza-Diels–Alder reaction
作者:Maria Luísa Cardoso do Vale、José Enrique Rodríguez-Borges、Olga Caamaño、Franco Fernández、Xerardo García-Mera
DOI:10.1016/j.tet.2006.06.118
日期:2006.10
glyoxylate-derived N-benzylimine with cyclopentadiene resulted in the enantioselective synthesis of the corresponding pure [(1S,3-exo)-2-benzyl-2-azabicyclo[2.2.1]hept-5-ene]-3-carboxylates (80 or 69% yield, respectively). Reduction of these cycloadducts with LiAlH4 afforded pure (−)-[(1S,3-exo)-2-benzyl-2-azabicyclo[2.2.1]hept-5-en-3-yl]methanol. Furthermore, a reaction sequence based on Barbier–Wieland
第(1个所述的非对称氮杂Diels-Alder反应[R)-8-苯基薄荷基或(1 - [R)-8- phenylisoneomenthyl乙醛酸衍生Ñ -benzylimine与环戊二烯导致相应的纯[(1的对映选择性合成小号,3 -外)-2-苄基-2-氮杂双环[2.2.1]庚-5-烯] -3-羧酸酯(80或69%产率,分别地)。用LiAlH 4还原这些环加合物得到纯的(-)-[((1 S,3- exo))-2-苄基-2-氮杂双环[2.2.1]庚-5-烯-3-基]甲醇。此外,基于Barbier-Wieland降解两种(1 S,3- exo)加合物的反应序列可得到纯的(+)-(1 R)-2-苯甲酰基-2-氮杂双环[2.2.1]庚-3-3-酮。在所提及的两个转化序列的过程中,以几乎定量的方式回收了手性助剂。