Total Synthesis of the Quinone Epoxide Dimer (+)-Torreyanic Acid: Application of a Biomimetic Oxidation/Electrocyclization/Diels-Alder Dimerization Cascade1

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• 作者：Chaomin Li ; Richard P. Johnson ; and John A. Porco ; Jr.
• 刊名：Journal of the American Chemical Society
• 出版年：2003
• 出版时间：April 30, 2003
• 年：2003
• 卷：125
• 期：17
• 页码：5095 - 5106
• 全文大小：371K
• 年卷期：v.125,no.17(April 30, 2003)
• ISSN：1520-5126

文摘

An asymmetric synthesis of the quinone epoxide dimer (+)-torreyanic acid (48) has beenaccomplished employing [4 + 2] dimerization of diastereomeric 2H-pyran monomers. Synthesis of the relatedmonomeric natural product (+)-ambuic acid (2) has also been achieved which establishes the biosyntheticrelationship between these two natural products. A tartrate-mediated nucleophilic epoxidation involvinghydroxyl group direction facilitated the asymmetric synthesis of a key chiral quinone monoepoxideintermediate. Thermolysis experiments have also been conducted on a model dimer based on the torreyanicacid core structure and facile retro Diels-Alder reaction processes and equilibration of diastereomeric2H-pyrans have been observed. Theoretical calculations of Diels-Alder transition states have beenperformed to evaluate alternative transition states for Diels-Alder dimerization of 2H-pyran quinone epoxidemonomers and provide insight into the stereocontrol elements for these reactions.