Enantioselective Synthesis of 15-<i>e</i><i>pi</i>-Haterumalide NA Methyl Ester and Revised Structure of Haterumalide NA

Kigoshi, Hideo; Kita, Masakazu; Ogawa, Seiji; Itoh, Masahiro; Uemura, Daisuke

doi:10.1021/ol0341804

Cited by 66 publications

(75 citation statements)

References 24 publications

(15 reference statements)

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“…Interestingly, haterumalide NA/oocydin A exhibited cytotoxicity against P388 leukemia (6) and breast (5) cancer cells. These broad biological impacts made the haterumalides/oocydins very attractive targets for total chemical synthesis, which has been achieved by several research groups (9,12,13).…”

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confidence: 99%

Bacterial Biosynthetic Gene Clusters Encoding the Anti-cancer Haterumalide Class of Molecules

Matilla

Stöckmann

Leeper

et al. 2012

Journal of Biological Chemistry

121

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Background: Oocydin A is an anticancer haterumalide with strong antimicrobial activity against agriculturally important plant pathogenic fungi and oomycetes. Results: The oocydin A gene cluster has been identified and characterized in four plant-associated enterobacteria. Conclusion:The ooc gene cluster is organized in three transcriptional units encoding enzymes that belong to a growing class of trans-acyltransferase polyketide synthases. Significance: Oocydin A has potential agricultural, pharmacological, and chemotherapeutic applications.

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confidence: 99%

Bacterial Biosynthetic Gene Clusters Encoding the Anti-cancer Haterumalide Class of Molecules

Matilla

Stöckmann

Leeper

et al. 2012

Journal of Biological Chemistry

121

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“…Enone 11 was synthesized by conversion of known15 carboxylic acid 10 to its corresponding Weinreb amide16 followed by reaction with isopropenyl Grignard reagent. Similarly, enone 13 and 14 were prepared from benzyloxyacetic acid 12 .…”

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confidence: 99%

L-Selectride-Mediated Highly Diastereoselective Asymmetric Reductive Aldol Reaction: Access to an Important Subunit for Bioactive Molecules

et al. 2008

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L-Selectride reduction of a chiral or achiral enone followed by reaction of the resulting enolate with optically active α-alkoxy aldehydes proceeded with excellent diastereoselectivity. The resulting α,α-dimethyl-β-hydroxy ketones are inherent to a variety of biologically active natural products.Asymmetric aldol reactions leading to the stereocontrolled generation of β-hydroxy carbonyl derivatives are among the most important reactions in organic synthesis. 1 Consequently, a number of effective methodologies have been developed over the years. In a series of elegant studies, Stork and co-workers have shown that lithium-ammonia reduction of enones leads to stoichiometric generation of enolates. 2 Since then, reductive aldol reactions in which conjugate reduction followed by aldol reaction of the resulting enolates led to the development of a wide variety of methodologies for the synthesis of β-hydroxy carbonyl derivatives. 3 In recent years, impressive progress has been made in both catalytic 4 and enantioselective 5 reductive aldol processes. In the context of our enantioselective synthesis of (+)-peloruside A, we recently carried out a L-selectride mediated reductive aldol coupling of enone 1 and aldehyde 2 to provide aldol product 3 and its diastereomer as a 4:1 mixture in 92% yield at −78 °C for 1 h. 6,7 The major aldolate 3 was subsequently converted to peloruside A. The overall process is quite practical and offers significant improvement over the direct aldol reaction of related ketone enolate and aldehyde reported recently. 8 Of particular importance, these α,α-dimethyl β-hydroxy carbonyl derivatives are structural features of numerous bioactive natural products like epothilones, 9 mycalamide A 10 and peloruside A. 6 Encouraged by the reasonable diastereoselectivity of the L-selectride mediated reductive aldol process, we have now examined the stereochemical outcome with a variety of chiral and achiral enones and aldehydes bearing an α-β-alkoxy stereocenter. Herein, we report the results of our investigations. Excellent levels of diastereoselectivity are attainable when the enolate from L-selectride reduction is reacted with aldehydes containing an α-chiral center.Our preliminary investigations focused on reactions with model 5 and optically active isopropylidene glyceraldehyde 4. As shown in Scheme 1, enone 5 was prepared in a two stepakghosh@purdue.edu . Supporting Information Available: Experimental procedures and 1 H-and 13 C-NMR spectra for all new compounds. This material is available free of charge via the Internet at http://pubs.acs.org. NIH Public Access Author ManuscriptOrg Lett. Author manuscript; available in PMC 2010 September 22. (1) reaction of isopropenyl magnesium bromide in diethyl ether followed by Dess-Martin oxidation 11 of the resulting diastereomeric alcohols to enone 5 in 63% yield in 2-steps. Enone 5 was treated with 1·1 equiv of L-selectride at −78 °C for 10 min to form the corresponding lithium enolate. To the resulting enolate, 2 equiv of isopropylidene-Dglyceraldehyde...

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“…(35). [62] 35 Several tandem oxidation/Diels±Alder reactions using 1 and 2 have also been applied in natural product synthesis. In the synthetic study toward the potent microtubule-stabilizing agent FR182877, oxidation of 51 with 2 buffered with solid sodium bicarbonate produced bicyclic products 52 via a tandem oxidation/ intramolecular Diels±Alder reaction, Eq.…”

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confidence: 99%

Hypervalent Iodine Reagents for the Oxidation of Alcohols and Their Application to Complex Molecule Synthesis

2004

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Hypervalent iodine(V) derivatives such as 2-iodoxybenzoic acid (IBX) and Dess±Martin periodinane [DMP; 1,1,1-tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)-one] have been used widely for the oxidation of alcohols to aldehydes and ketones during the last decade because of their high chemoselectivity, mild reactivity, and high yielding process. This review focuses on the recent progress in the oxidation of alcohols to carbonyl compounds using IBX, DMP, and other hypervalent iodine reagents, and their application to total syntheses of a variety of complex natural products.

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Enantioselective Synthesis of 15-epi-Haterumalide NA Methyl Ester and Revised Structure of Haterumalide NA

Cited by 66 publications

References 24 publications

Bacterial Biosynthetic Gene Clusters Encoding the Anti-cancer Haterumalide Class of Molecules

Bacterial Biosynthetic Gene Clusters Encoding the Anti-cancer Haterumalide Class of Molecules

L-Selectride-Mediated Highly Diastereoselective Asymmetric Reductive Aldol Reaction: Access to an Important Subunit for Bioactive Molecules

Hypervalent Iodine Reagents for the Oxidation of Alcohols and Their Application to Complex Molecule Synthesis

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