Synthetic approaches to the powerful analgesic alkaloids (+)- and (â)-epibatidine are described. The starting material employed was natural (â)-quinic acid from which chiral enones and α-iodoenones were prepared. Stille coupling afforded suitable substrates for completion of the syntheses. A key step in this process was the diastereoselective reduction of a cyclohexanone with sodium borohydride and DMSO which sets up the stereochemistry necessary for the formation of the bicycloheptane system. The synthesis of a previously reported enone intermediate has also been improved.
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本文介绍了强效镇痛
生物碱(+)-和(â)-表巴丁的合成方法。采用的起始原料是天然(â)-
奎宁酸,并从中制备了手性烯酮和δ-
碘烯酮。斯蒂尔偶联为完成合成提供了合适的底物。这一过程中的一个关键步骤是用
硼氢化钠和
二甲基亚砜对
环己酮进行非对映选择性还原,从而建立了形成双
环庚烷体系所需的立体
化学结构。之前报道的一种烯酮中间体的合成方法也得到了改进。