Stereoselective Total Syntheses of Guanacastepenes N and O

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• 作者：Shao-Zheng Peng ; Chin-Kang Sha
• 刊名：Organic Letters
• 出版年：2015
• 出版时间：July 17, 2015
• 年：2015
• 卷：17
• 期：14
• 页码：3486-3489
• 全文大小：468K
• ISSN：1523-7052

文摘

Total syntheses of (卤)-guanacastepenes N and O were accomplished with 2-cycloheptenone as starting material. The six- and five-membered rings of the core [5, 7, 6] ring skeleton were constructed with an intramolecular Diels鈥揂lder reaction and 伪-carbonyl radical cyclization. The quaternary centers and their stereochemistry were established with sequential Cu(I)-mediated conjugate additions. A sequence with dihydroxylation, conjugate addition, and 尾-elimination was devised to incorporate all oxygen functionalities at positions. The total synthesis is adaptable for the synthesis of enantiopure guanacastepenes N and O using chiral intermediate (R)-3-vinyl-2-cycloheptenol obtained from lipase-catalyzed kinetic resolution.