Total synthesis of (+)-β-erythroidine
Total synthesis of (+)-β-erythroidine
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DOI：
10.1002/anie.200600210
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发表时间：
2006-01-01
影响因子：
16.6
通讯作者：
Hatakeyama, S
中科院分区：
文献类型：
--
作者：
Fukumoto, H;Takahashi, K;Hatakeyama, S
刺桐生物碱[1]由于其有趣的生物活性[2]和特征性的缩聚结构，在过去的几十年中受到了相当大的关注，这为开发新的成环方法提供了机会。[3]根据其结构特征，该生物碱家族可分为两类：D环为芳香族的生物碱和D环含有不饱和内酯的生物碱。虽然已经开发了各种各样的方法来合成含有芳香族D环的基团，[1，3]但其具有非芳香族D环的对应物的合成仅限于Kitahara及其同事的（N）-cocculolidine的合成。[3p]本文中，我们描述了（+）-b-赤藓定（1），一种非芳香族二烯型刺桐生物碱分离自刺桐属的几个物种连同aerythroidine的第一个全合成。[4，5]最近，我们开发了一种有效的方法[3 j，6]，用于构建依赖于二烯炔的闭环复分解[7，8]的阿立南骨架。基于该方法，我们设想二烯炔2作为1的前体，并假设该中间体可以从酮基酯3获得，其可以从5至4通过N-烷基化随后通过Dieckmann缩合获得（方案1）。在这个合成计划中，另一个必须解决的关键问题是乙炔化氨基酸片段5的对映体控制结构，它含有一个四元中心。
The Erythrina alkaloids [1] have received considerable attention over the past few decades owing to their intriguing biological activity [2] and characteristic polycondensed structures, which provide an opportunity to develop a new ringforming methodology.[3] This family of alkaloids are classified into two groups according to their structural features: those whose D rings are aromatic, and those whose D rings contain an unsaturated lactone. Although a wide variety of methods have already been developed for the synthesis of the group containing an aromatic Dring,[1, 3] the synthesis of their counterparts with non-aromatic D rings is limited to that of (Æ)-cocculolidine by Kitahara and co-workers.[3p] Herein, we describe the first total synthesis of (+)-b-erythroidine (1), a non-aromatic dienoid-type Erythrina alkaloid isolated from several species of the Erythrina genus together with aerythroidine.[4, 5]Recently, we developed an efficient method [3j, 6] for the construction of the erythrinan skeleton which relies on ringclosing metathesis [7, 8] of a dienyne. On the basis of this methodology, we envisaged dienyne 2 as a precursor of 1 and postulated that this intermediate could be accessed from bketo ester 3, which would be available from 5 through 4 by N-alkylation followed by Dieckmann condensation (Scheme 1). In this synthetic plan, another key issue which must be addressed is the enantiocontrolled construction of ethynylated amino acid fragment 5, which contains a quaternary center.