Concise Total Syntheses of Variecolortides A and B through an Unusual Hetero‐Diels–Alder Reaction

Kuttruff, Christian A.; Zipse, Hendrik; Trauner, Dirk

doi:10.1002/anie.201006154

Cited by 50 publications

(26 citation statements)

References 22 publications

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“… Quinolone Quinolactacin A1, Quinolactacin A2, Quinolactacin B Visagie et al. 2017 A. megasporus Chimeric echinulins and auroglaucins Cryptoechinulin B (= aurechinulin), (+) and (−)-cryptoechinulin D, 7-O-methylvariecolortide A, variecolortide A, (+) & (−) variecolortide B, (+) & (−) variecolortide C, (+) & (−) 7-isopentenylcryptoechinuline D, dihydrocryptoechinulin D, effusin A Gatti et al., 1976 , Inoue et al., 1977b , Li et al., 2010 , Wang et al., 2007b (misidentified as A. variecolor ); Kuttruff et al., 2011 , Yan et al., 2012 , Gao et al., 2012b (misidentified as A. effusus ), Gao et al. 2013 (misidentified as A. effusus ), Chen et al.…”

Section: Resultsmentioning

confidence: 99%

Polyphasic taxonomy of Aspergillus section Aspergillus (formerly Eurotium), and its occurrence in indoor environments and food

Chen¹,

Hubka²,

Frisvad³

et al. 2017

Studies in Mycology

115

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Aspergillus section Aspergillus (formerly the genus Eurotium) includes xerophilic species with uniseriate conidiophores, globose to subglobose vesicles, green conidia and yellow, thin walled eurotium-like ascomata with hyaline, lenticular ascospores. In the present study, a polyphasic approach using morphological characters, extrolites, physiological characters and phylogeny was applied to investigate the taxonomy of this section. Over 500 strains from various culture collections and new isolates obtained from indoor environments and a wide range of substrates all over the world were identified using calmodulin gene sequencing. Of these, 163 isolates were subjected to molecular phylogenetic analyses using sequences of ITS rDNA, partial β-tubulin (BenA), calmodulin (CaM) and RNA polymerase II second largest subunit (RPB2) genes. Colony characteristics were documented on eight cultivation media, growth parameters at three incubation temperatures were recorded and micromorphology was examined using light microscopy as well as scanning electron microscopy to illustrate and characterize each species. Many specific extrolites were extracted and identified from cultures, including echinulins, epiheveadrides, auroglaucins and anthraquinone bisanthrons, and to be consistent in strains of nearly all species. Other extrolites are species-specific, and thus valuable for identification. Several extrolites show antioxidant effects, which may be nutritionally beneficial in food and beverages. Important mycotoxins in the strict sense, such as sterigmatocystin, aflatoxins, ochratoxins, citrinin were not detected despite previous reports on their production in this section. Adopting a polyphasic approach, 31 species are recognized, including nine new species. ITS is highly conserved in this section and does not distinguish species. All species can be differentiated using CaM or RPB2 sequences. For BenA, Aspergillus brunneus and A. niveoglaucus share identical sequences. Ascospores and conidia morphology, growth rates at different temperatures are most useful characters for phenotypic species identification.

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Section: Resultsmentioning

confidence: 99%

Polyphasic taxonomy of Aspergillus section Aspergillus (formerly Eurotium), and its occurrence in indoor environments and food

Chen¹,

Hubka²,

Frisvad³

et al. 2017

Studies in Mycology

115

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“…In agreement with this consideration, variecolortide A (240a) is obtained in 48% yield when diketopiperazine isoechinulin B (241a) and hydroxyviocristin (243) are heated at 180 1C under aerobic conditions (Scheme 55). 125 Variecolortide B (240b) is also generated from 241b and 243 in 32% yield under the same conditions. It is conceivable that the reactions proceed through the hetero-Diels-Alder reaction of exo-methylene diketopiperazines 241 with the quinone methide tautomer of 243, followed by rapid oxidation of the labile benzylic C-H bond of adduct 244 in the presence of air.…”

Section: Biomimetic Synthesis Of Natural Compounds Using Hetero-dielsmentioning

confidence: 99%

5.10 Hetero-Diels–Alder Reactions

Ishihara¹,

Sakakura²

2014

Comprehensive Organic Synthesis II

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“…这些工作都值得我们在以后的合成工作中去借鉴. [35] 报道了天然产物 Variecolortides A 和 B 的全合成. Variecolortides A 和 B 是 2007 年由朱伟明课题组 [36] 通过对天然产物 Variecolortides A 和 B 结构分析可以发现, Variecolortides A 和 B 是由另外两个天然产物构成的: Hydroxyviocristin 53(分离于冠突曲霉 Aspergillus cristatus) [37] 和 Isoechinulins 55a, 55b( 分离于赤曲霉 Aspergillus ruber) [38] .…”

unclassified

“…Variecolortides A 和 B 是 2007 年由朱伟明课题组 [36] 通过对天然产物 Variecolortides A 和 B 结构分析可以发现, Variecolortides A 和 B 是由另外两个天然产物构成的: Hydroxyviocristin 53(分离于冠突曲霉 Aspergillus cristatus) [37] 和 Isoechinulins 55a, 55b( 分离于赤曲霉 Aspergillus ruber) [38] . 于是 Trauner 及其同事们提出可以利用 Hydroxyviocristin (53)原位生成 o-QM 中间体和 Isoechinulins 55a, 55b 经过串联仿生 Hetero-Diels-Alder reaction 和氧化反应构建目标天然产物的分子骨架螺环 N,O-缩醛结构 [35] . 2.8 o-QMs 在 Heliananes 家族天然产物合成工作中的应用 2011 年 Pettus 课题组 [39] 报道了天然产物 Heliananes 家族的合成工作, Crews 等 [40] 在众多来自自然界的天然产物中, 含有四氢苯并吡喃多环母核结构的很多天然产物都具有很好的生物活性, 有些被用于降血压药, 还有些因其具有良好的细胞毒性而具有被开发为抗癌药的潜力 [41] .…”

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Applications ofortho-Quinone Methides in the Synthesis of Natural Products

Ai¹,

Liao²,

Lei³

2015

Chin. J. Org. Chem.

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ortho-Methylene cyclohexadienones, which are collectivelly referred to as ortho-quinone methides (o-QMs), were first suggested by Fries in 1907. o-QMs are a kind of short-lived and highly reactive versatile intermediates in organic synthesis. The unstability nature of o-QMs is due to their propensity to undergo rapid rearomatisation either by Michael addition of nucleophiles or, often more usefully, by cycloaddition with 2π partners or via oxa-6π-electrocyclisation to give benzopyrans. ortho-Quinone methides were always used in the synthesis of natural products through Michael addition and cycloaddition. As a new member of the family of inherently reactive species, ortho-quinone methides are similar with radicals, carbocations, carbenes, etc. And now using o-QMs to form skeletons of natural products has become a very useful stratergy. This review contains the major application in the synthesis of natural products during 2009 to 2014. Keywords ortho-quinone methide; natural products; organic synthesis 1 背景介绍邻甲亚基环己二烯酮, 系统命名为 6-甲亚基-环己-2,4-二烯酮(6-methylene-cyclohexa-2,4-dienone), 该结构也被统称为 ortho-Quinone methides (o-QMs), 其结构如 1 (Scheme 1). 1907 年 Fries 课题组 [1] 首次提出了 o-QMs 这个概念, 并基于这个概念解释了反应过程中产生二聚和三聚产物的原因. 虽然邻甲亚基环己二烯酮中间体这个概念很早就被提出, 但是因为它自身的不稳定性、高反应活性和极短的半衰期, 直到几十年后才由 McIntosh 和 Chapman [2] 用低温红外光谱证明了这个活泼中间体的存在. 而它存在的第一个直接证据则是在 1998 年由 Amouri 等得到的 o-QM 和 IrCp* (Cp*＝五甲基环戊二烯)所形成的 π-配合物 X-ray 单晶结构 [3]. 邻甲亚基环己二烯酮中间体十分倾向于快速的再芳构化, 这决定了它高活泼性的特点.

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Concise Total Syntheses of Variecolortides A and B through an Unusual Hetero‐Diels–Alder Reaction

Cited by 50 publications

References 22 publications

Polyphasic taxonomy of Aspergillus section Aspergillus (formerly Eurotium), and its occurrence in indoor environments and food

Polyphasic taxonomy of Aspergillus section Aspergillus (formerly Eurotium), and its occurrence in indoor environments and food

5.10 Hetero-Diels–Alder Reactions

Applications ofortho-Quinone Methides in the Synthesis of Natural Products

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