Convergent synthesis of the common FGHI-ring part of ciguatoxins

Takizawa, Ayumi; Fujiwara, Kenshu; Doi, Eriko; Murai, Akio; Kawai, Hidetoshi; Suzuki, Takanori

doi:10.1016/j.tet.2006.05.014

Cited by 19 publications

(6 citation statements)

References 116 publications

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“…After tert -butyldimethylsilyl (TBS) protection, subsequent desilylation afforded the terminal alkyne 26 , which was lithiated and then quenched with methyl iodide to furnish a one-carbon-more homologue 27 . Regioselective hydrozirconation of 27 was achieved smoothly to yield 28 (11:1 regioselectivity in the preference of 28 ) after iodine quench . Deprotection of 28 produced a primary alcohol 29 , which was then oxidized to aldehyde 30 with DMP.…”

Section: Resultsmentioning

confidence: 99%

Structural Elucidation and Bioinspired Total Syntheses of Ascorbylated Diterpenoid Hongkonoids A–D

Zhao

Wang

et al. 2018

J. Am. Chem. Soc.

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Hongkonoids A-D (1-4), the first example of ascorbylated terpenoids featuring a unique 5,5,5-fused tricyclic spiroketal butyrolactone moiety and diterpenoid-derived long chain, were isolated from Dysoxylum hongkongense. Their structures were unambiguously assigned by a combination of spectroscopic data, chemical degradation, X-ray crystallography, CD analysis, and total synthesis. The total syntheses of compounds 1-4 were effectively accomplished by a convergent strategy with the longest linear sequences of 12-14 steps and overall yields of 5.4-9.6%. Notably, we exploited a bioinspired one-pot method to construct the key intermediate 14 from an easily made compound 12 by involving the cascade reactions of an elaborate Claisen rearrangement, deprotections, and a 5-exo-trig cyclization. The desired major epimer 14a was then transformed to the main building block 21. Assembly of 21 and the long chain vinyl iodide 7 was made by an NHK coupling reaction to furnish the framework of 1-4. Some of the hongkonoids and/or synthetic analogs showed significant to moderate inhibitory activities against NF-κB, 11β-HSD1, and sterol synthesis. The most active NF-κB inhibitor 34 exhibited distinct inhibition on the LPS-induced inflammatory responses in RAW 246.7 and primary BMDM cells.

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Section: Resultsmentioning

confidence: 99%

Structural Elucidation and Bioinspired Total Syntheses of Ascorbylated Diterpenoid Hongkonoids A–D

Zhao

Wang

et al. 2018

J. Am. Chem. Soc.

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“…Intermediate alcohol 4 was protected as its TBS ether, and hydrogenolysis of benzyl ether in ethyl acetate afforded primary alcohol 10 in high yield (Scheme ). To install three additional carbons at C6, S N 2-type alkyne substitution was employed. Triflation of primary alcohol 10 using Tf 2 O gave an unstable intermediate triflate ester that was used without purification.…”

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confidence: 99%

Total Synthesis of Brevisamide

Lee

Panek

2009

Org. Lett.

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“…Other natural products, such as carolacton, 75 the (+)-and (−)-bisanthraquinone antibiotic BE-43472B, 76 or the common FGHI-ring of ciguatoxins, 77 have been successfully synthesized using NHTK coupling in an intermolecular fashion to construct the 2-methyl-2-en-ol scaffold present in all these compounds. Norrisolide was synthesized using the NHTK reaction between a quaternary nonmethylated vinyl triflate and the corresponding aldehyde (Figure 2).…”

Section: Intermolecular Versionmentioning

confidence: 99%

Role of the Nozaki–Hiyama–Takai–Kishi Reaction in the Synthesis of Natural Products

2017

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The Nozaki-Hiyama-Takai-Kishi (NHTK) reaction was discovered in the late 1970s and, since then, its main application has been its use in total synthesis. In this comprehensive review, the efficiency of the NHKT reaction in the synthesis of a great number of different scaffolds present in complex natural products is analyzed. The preparation of enol and allylic and propargylic alcohol motifs is discussed, highlighting factors such as yield, chemoselectivity, stereoselectivity, or the importance of protecting groups. The review is divided into two main sections: intermolecular and intramolecular NHTK reactions. A final discussion about the current "state-of-art" and future perspectives for the use of this transformation in total synthesis is also included.

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Convergent synthesis of the common FGHI-ring part of ciguatoxins

Cited by 19 publications

References 116 publications

Structural Elucidation and Bioinspired Total Syntheses of Ascorbylated Diterpenoid Hongkonoids A–D

Structural Elucidation and Bioinspired Total Syntheses of Ascorbylated Diterpenoid Hongkonoids A–D

Total Synthesis of Brevisamide

Role of the Nozaki–Hiyama–Takai–Kishi Reaction in the Synthesis of Natural Products

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