Total Synthesis of Lingzhiol and its Analogues through the Wittig Reaction of an Oxocyclopentane Carboxylate

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• 作者：Rathikrishnan Rengarasu and Prof. Dr. Martin E. Maier
• 刊名：Asian Journal of Organic Chemistry
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：6
• 期：1
• 页码：108-117
• 全文大小：1407K
• ISSN：2193-5815

文摘

The biosynthesis of polycyclic natural product lingzhiol (1) through an intramolecular Friedel–Crafts alkylation reaction of an aryl-substituted cyclopentane epoxide (22) was attempted. The synthesis of this endocyclic epoxide involved the alkylation of cyclopentane carboxylate 14 with alkyl iodide 25 to afford ketoester 26. Subsequent Wittig olefination led to exocyclic alkene exo-15 in good yield. Epoxidation, opening of the epoxide to generate allyl alcohol 29, and a second epoxidation reaction afforded compounds 22 and 31. However, presumably owing to stereoelectronic effects, the cyclization of these substrates into polycycles 17 and 32, respectively, was unsuccessful. Nevertheless, the Wittig reaction to afford exo-15 allowed us to converge with the previously reported route of Qin et al., which featured the cyclization of spiro epoxide 16. Thus, lingzhiol is now available in only nine steps. Various analogues of lingzhiol were also prepared, including desoxy derivative 37, quinone 38, mono-methoxy-deoxy derivative 39, and ketone 40.