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 mater ial, 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-tri methylcyclohexane- 1,3,5-tricarboxylic acid (Kemp's triacid). For the synth esis of the diastereomeric menthyl esters 1 and 2, the chloride 4 was initi ally substituted by (-)-menthol and its imide part was subsequently reduced to an amide by consecutive treatment with sodium borohydride and triethyls ilane. The enantiomerically pure hosts 3a and 3b were obtained from the rac emate by resolution of their N-menthoxycarbonyl derivatives. The racemic co mpounds rac-3a and rac-3b were prepared from the acid chloride 4 and the or tho-hydroxyanilines 9a and 9b via amide formation, condensation to the oxaz ole and reduction. Structural data are provided which prove the absolute co nfiguration of compound ent-3b and the relative configuration of compound, rac-3a.