Total synthesis of the quinone epoxide dimer (+)-torreyanic acid: Application of a biomimetic oxidation/electrocyclization/Diels-Alder dimerization cascade
Total synthesis of the quinone epoxide dimer (+)-torreyanic acid: Application of a biomimetic oxidation/electrocyclization/Diels-Alder dimerization cascade
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DOI：
10.1021/ja021396c
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发表时间：
2003-04-30
影响因子：
15
通讯作者：
Porco, JA
中科院分区：
文献类型：
--
作者：
Li, CM;Johnson, RP;Porco, JA
利用非对映体 2H-吡喃单体的 [4 + 2] 二聚化，完成了醌环氧化物二聚体 (+)-香槠酸 (48) 的不对称合成。还实现了相关单体天然产物(+)-苯丁酸(2)的合成，建立了这两种天然产物之间的生物合成关系。涉及羟基方向的酒石酸介导的亲核环氧化促进了关键手性醌单环氧化物中间体的不对称合成。还对基于香桧酸核心结构的模型二聚体进行了热解实验，并观察到了简单的逆狄尔斯-阿尔德反应过程和非对映体 2H-吡喃的平衡。已经进行了狄尔斯-阿尔德过渡态的理论计算，以评估 2H-吡喃醌环氧化物单体的狄尔斯-阿尔德二聚的替代过渡态，并深入了解这些反应的立体控制元素。
An asymmetric synthesis of the quinone epoxide dimer (+)-torreyanic acid (48) has been accomplished employing [4 + 2] dimerization of diastereomeric 2H-pyran monomers. Synthesis of the related monomeric natural product (+)-ambuic acid (2) has also been achieved which establishes the biosynthetic relationship between these two natural products. A tartrate-mediated nucleophilic epoxidation involving hydroxyl group direction facilitated the asymmetric synthesis of a key chiral quinone monoepoxide intermediate. Thermolysis experiments have also been conducted on a model dimer based on the torreyanic acid core structure and facile retro Diels-Alder reaction processes and equilibration of diastereomeric 2H-pyrans have been observed. Theoretical calculations of Diels-Alder transition states have been performed to evaluate alternative transition states for Diels-Alder dimerization of 2H-pyran quinone epoxide monomers and provide insight into the stereocontrol elements for these reactions.