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
作者:Thorsten Bach、Hermann Bergmann、Benjamin Grosch、Klaus Harms、Eberhardt Herdtweck
DOI:10.1055/s-2001-15231
日期:——
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.
本文介绍了标题化合物的合成过程。作为常见的起始原料,1,5,7-三甲基-2,4-二氧代-3-氮杂双环[3.3.1]-壬烷-7-羧酸氯化物(4)可从顺式、顺式-1,3,5-三甲基环己烷-1,3,5-三羧酸(坎普三酸)中获得。在合成非对映的薄荷酯 1 和 2 时,首先用(-)-薄荷醇取代氯化物 4,然后用硼氢化钠和三乙基硅烷连续处理,将其酰亚胺部分还原成酰胺。通过解析其 N-薄荷氧羰基衍生物,从外消旋体中得到了对映体纯度为 3a 和 3b 的主化合物。外消旋化合物 rac-3a 和 rac-3b 是由酰氯 4 和正羟基苯胺 9a 和 9b 通过酰胺形成、缩合成噁唑和还原反应制备的。所提供的结构数据证明了化合物 ent-3b 的绝对构型和化合物 rac-3a 的相对构型。