Synthesis of Enantiomerically Pure 1,5,7-Trimethyl-3-azabicyclo[3.3.1]nonan-2-ones as Chiral Host Compounds for Enantioselective Photochemical Reactions in Solution
The synthesis of the title compounds is described. As common starting material, 1,5,7-trimethyl-2,4-dioxo-3-azabicyclo[3.3.1]-nonan-7-carboxylic acid chloride (4) was employed which is in turn available from cis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid (Kemp’s triacid). For the synthesis of the diastereomeric menthyl esters 1 and 2, the chloride 4 was initially substituted by (-)-menthol and its imide part was subsequently reduced to an amide by consecutive treatment with sodium borohydride and triethylsilane. The enantiomerically pure hosts 3a and 3b were obtained from the racemate by resolution of their N-menthoxycarbonyl derivatives. The racemic compounds rac-3a and rac-3b were prepared from the acid chloride 4 and the ortho-hydroxyanilines 9a and 9b via amide formation, condensation to the oxazole and reduction. Structural data are provided which prove the absolute configuration of compound ent-3b and the relative configuration of compound rac-3a.
A Chiral Thioxanthone as an Organocatalyst for Enantioselective [2+2] Photocycloaddition Reactions Induced by Visible Light
作者:Rafael Alonso、Thorsten Bach
DOI:10.1002/anie.201310997
日期:2014.4.22
Thioxanthone 1, which was synthesized in a concise fashion from methyl thiosalicylate, exhibits a significant absorption in the visiblelight region. It allows for an efficient enantioselective catalysis of intramolecular [2+2] photocycloadditionreactions presumably by triplet energy transfer.
作者:Jeong, Kyu-Sung、Parris, Kevin、Ballester, Pablo、Rebek, Julius
DOI:——
日期:——
Assignment of the absolute configuration of 7-substituted 3-azabicyclo[3.3.1]nonan-2-ones by NMR-titration experiments
作者:Andreas Bauer、Thorsten Bach
DOI:10.1016/j.tetasy.2004.10.008
日期:2004.11
The configuration assignment of 7-substituted 3-azabicyclo[3.3.1]nonan-2-ones 2-5 was made possible using the known chiral lactam 1 as a reference compound. Lactam 1 formed exclusively heterochiral complexes with the compounds under investigation. The detection of these complexes was possible by H-1 NMR. The downfield shift of the NH proton in compounds 2-5 indicated complex formation whereas the NH-signal remained unchanged in homochiral systems. The phenomenon somewhat resembles an (inverse) molecular handshake. Only heterochiral compounds can interact whereas homochiral compounds do not fit together. (C) 2004 Elsevier Ltd. All rights reserved.