Total synthesis and structural refinement of the cyclic tripyrrole pigment nonylprodigiosin
Total synthesis and structural refinement of the cyclic tripyrrole pigment nonylprodigiosin
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DOI：
10.1021/jo991021i
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发表时间：
1999-10-29
影响因子：
3.6
通讯作者：
Lehmann, CW
中科院分区：
文献类型：
--
作者：
Fürstner, A;Grabowski, J;Lehmann, CW
首次全合成了环状灵芝菌素衍生物4，它是一种潜在的开发免疫抑制剂的先导化合物。该方法的关键步骤包括钯催化的相当不稳定的吡咯硼酸衍生物17与富含电子的三氟化吡咯15的Suzuki交叉偶联反应，然后生成的二烯的闭环歧化反应(RCM)以形成目标分子的大环环。这种转化最好的实现方法是使用亚铟Ru络合物21作为预催化剂。产物18HCl的X射线数据表明，互变异构体B很好地描述了该生物碱的杂芳环中的电子分布，其中中心环构成了吡咯基吡咯亚甲基发色团中的氮杂富烯单元。
The first total synthesis of the cyclic prodigiosin derivative 4 is described, which constitutes a potential lead compound for the development of immunosuppressive agents. The key steps of this approach comprise a palladium-catalyzed Suzuki cross coupling reaction of the rather unstable pyrrole boronic acid derivative 17 with the electron rich pyrrolyl triflate 15 followed by a ring-closing metathesis reaction (RCM) of the resulting diene to form the macrocyclic ring of the target molecule. This transformation is best achieved by using the ruthenium indenylidene complex 21 as precatalyst. X-ray data of product 18.HCl thus formed suggest that the tautomeric form B properly describes the electron distribution within the heteroaromatic segment of this alkaloid, in which the central ring constitutes the azafulvene unit of the pyrrolylpyrromethene chromophore.