A stereoselective synthesis of the spirosesquiterpene (−)-acorenone

Lange, Gordon L.; Orrom, Will J.; Wallace, D. J.

doi:10.1016/s0040-4039(01)83542-5

Cited by 10 publications

(2 citation statements)

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“…Thus, in comparable reactions, a vicinal methyl substituent on a five‐ or six‐membered ring induced a selectivity of 80:206g or 90:10,7a respectively, whereas the bulky isopropyl substituent on a five‐membered ring led to selectivities exceeding 92:8 6g. 7b,c…”

Section: Resultsmentioning

confidence: 99%

Spirodionic Acid, a Novel Metabolite from Streptomyces sp., Part 2: Total Synthesis through a Twofold Michael Addition as a Selective Spiroannelation Strategy

Siewert¹,

Textor²,

Grond³

et al. 2007

Chemistry A European J

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To elucidate the structure of the new natural product spirodionic acid, which has three stereogenic centers of hitherto unknown configuration, two 4-ethenylspiro[4.5]dec-6-en-1,8-diones with opposite relative configuration at C4 and C5 were prepared. The first access involved the synthesis of 3-ethenyl-2-formylcyclopentanone (8) using a three-component coupling process. A sequence of Michael addition to penten-3-one (7) and intramolecular aldol condensation then led to the highly selective formation of the 4S*,5S*-configured spirocycle 5. In contrast, a selective spiroannelation of a cyclohexenone ring was accomplished by a novel type of twofold Michael addition to the dialkenyl ketone 11 with subsequent dehydrogenation to furnish the 4S*,5R*-configured spirocycle 25. Diastereoselective methylation and oxidative degradation then completed a highly efficient synthesis of the natural product as prerequisite for the assignment of its absolute configuration.

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Section: Resultsmentioning

confidence: 99%

Spirodionic Acid, a Novel Metabolite from Streptomyces sp., Part 2: Total Synthesis through a Twofold Michael Addition as a Selective Spiroannelation Strategy

Siewert¹,

Textor²,

Grond³

et al. 2007

Chemistry A European J

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“…For this purpose, the absolute configuration of natural 21 had to be established. Although several enantioselective routes were already known, [41][42][43] we felt that it would be more interesting to develop a new synthetic method rather than just repeating a known route to obtain the required reference compound. Trichoderma fungi are widespread plant-growth-promoting symbionts 44 that live in soil, root, and foliar ecosystems.…”

Section: Total Synthesis Of Glaciapyrrole a And Tricho-acorenolmentioning

confidence: 99%

Microbial Terpenes: A Perspective on Their Chemistry and Biosynthesis

Citron

Dickschat

2014

Synlett

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This personal account summarizes our ongoing work on the bioorganic chemistry of diverse microbial terpenoids. First, two selected total syntheses that were recently completed in our group are presented. We then show how the fundamental technique for our analytical work, closed-loop stripping apparatus (CLSA) in combination with gas chromatography/mass spectrometry (GC/MS), can be used to efficiently identify volatile natural products from various bacteria and fungi. The largest compound class among these volatiles is the terpenes. The CLSA technique can also be successfully applied to study interesting problems of the sometimes puzzling biosynthetic pathways towards terpenes. For this purpose we have developed two new CLSA-based methods, the first using 13 C-labeled precursors in feeding studies which allow for structure elucidations of microgram amounts of terpenes in complex headspace mixtures, and the second, a genome-mining approach via heterologous expression for the rapid chemical characterization of bacterial terpene cyclases. Recent developments in our laboratory include mechanistic investigations based on enzyme structural data in combination with site-specific mutations of terpene cyclases. 1 Introduction 2 Total Synthesis of Glaciapyrrole A and Tricho-acorenol 3 Feeding Experiments with Deuterated Precursors 4 The IspH Reaction 5 Feeding Experiments with 13 C-Labeled Precursors 6 Genome Mining and Closed-Loop Stripping Apparatus 7 Conclusion

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