The Suzuki Coupling Reaction in the Stereocontrolled Synthesis of 9-<i>cis</i>-Retinoic Acid and Its Ring-Demethylated Analogues<sup>,</sup><sup>1</sup>
作者:Yolanda Pazos、Beatriz Iglesias、Angel R. de Lera
DOI:10.1021/jo010711v
日期:2001.12.1
thallium-accelerated Suzuki coupling reaction of tetraenyl iodide 19 and cyclohexenyl boronate 18 afforded ethyl 9-cis-retinoate (12) in high yield. Both coupling partners of the Suzuki reaction are better reacted immediately after generation from their precursors, tetraenylstannane 10 and cyclohexenyl iodide 13. The geometrically homogeneous tetraenylstannane 10, comprising the polyenic side chain of ethyl 9-cis-retinoate
enyl加速碘化四烯基碘化物19和环己烯基硼酸酯18的Suzuki偶联反应,可高产率获得9-顺式-视黄酸乙酯(12)。Suzuki反应的两个偶合伙伴在从其前体四烯基锡烷10和环己烯基碘13生成后,立即能更好地反应。在几何上均匀的四烯基锡烷10包括9-顺-视黄酸乙酯及其环脱甲基类似物的多烯侧链。由立体选择性霍纳-沃兹沃思-埃蒙斯反应合成。另一方面,容易获得的环己酮是制备合成环修饰的9-顺-视黄酸类似物所需的环己烯基硼酸酯的理想起始原料。对于受阻的环己酮,将azo酮转化为环己烯基碘化物。然后进行碘-锂交换并用B(OMe)(3)捕集,得到环己烯基硼酸酯。如果前体环己酮具有仲碳,则通过消除在用正丁基锂处理三甲hydr时获得的C,N-二甲硅烷基化的中间体(Shapiro反应)来方便地形成烯基锂物质。上述方法均不能使2-甲基环己酮生成更多取代的有机锂。但是,交替的34和10的Stille交叉偶联得到9