Pyrazine Chemistry. V. Synthesis of Methylanhydropicroroccellin and Dimethylpicroroccellin

Marcuccio, Sebastian M.; Elix, JA

doi:10.1071/ch9851785

Cited by 20 publications

(25 citation statements)

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“…The D 3,14 double bond in 2 was deduced to be Z configuration from the relative downfield shift of H-14 (d H 6.81), in comparison with the vinyl proton chemical shifts of H-7 (d H 7.03) in nocazine C, 24 and H-7 (d H 6.54) in (3S,6E)-3-benzyl-6-benzylidenepiperazine-2,5-dione, 25 based on previous reports that the (Z)-vinyl proton was farther downfield than the (E)-vinyl proton because of the deshielding effect of the 5-ketone in DKP compounds. [24][25][26][27] Consistent with the Z configuration of D Figure S3). Marfey's method was applied to determine the absolute configuration of the phenylalanine moiety in 2.…”

Section: Structure Elucidationsupporting

confidence: 75%

New diketopiperazine derivatives from a deep-sea-derived Nocardiopsis alba SCSIO 03039

Zhang

Chen

et al. 2012

J Antibiot

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The strain SCSIO 03039 was isolated from a sediment sample in the Indian Ocean and was characterized as a Nocardiopsis alba species on the basis of its 16S rRNA gene sequence. Seven diketopiperazines (DKPs), including two new DKPs nocazines D (2a) and E (2b), and five known DKPs (1, 3-6), were isolated from N. alba SCSIO 03039, along with two known compounds 2-methoxy-1,4-naphthoquinone (7) and 1-hydroxy-4-methoxy-2-naphthoic acid (8). Their structures were elucidated by mass and NMR spectroscopic analyses. The structure of methoxyneihumicin (1), previously proposed in a conference poster lacking publicly available experimental data, was validated for the first time by detailed NMR analyses and X-ray diffraction study. The two enantiomers nocazines D (2a) and E (2b) were isolated as a mixture. Compounds 3 and 4 were only known as synthetic compounds before. Methoxyneihumicin (1) exhibited in vitro cytotoxicities against MCF-7 and SF-268 with IC₅₀ values of 4.6 and 12.7 μM, respectively, better than those of 6 (22.0 and 20.6 μM). The other compounds showed less pronounced cytotoxities against three tested human cancer cell lines and no compounds displayed antibacterial activities toward four indicator strains.

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Section: Structure Elucidationsupporting

confidence: 75%

New diketopiperazine derivatives from a deep-sea-derived Nocardiopsis alba SCSIO 03039

Zhang

Chen

et al. 2012

J Antibiot

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“…Scheme 4 Dimethyldioxirane [19,20] has become a reliable reagent in epoxidation of N-acylenamine moieties. [21][22][23][24] Its reaction with dihydroimidazo[2,1-a]isoquinolines 5 was highly stereoselective (dr Ͼ 95:5) affording excellent yields of the oxiranes 8a,b (see Scheme 2). MCPBA was successfully applied in the epoxidation of an anthraquinone-derived acylenamine.…”

Section: Resultsmentioning

confidence: 99%

Asymmetric Synthesis of Isoquinoline Derivatives from Amino Acids

2005

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Reaction of isoquinolines 1 with N-arylsulfonylamino acid fluorides 2 provides a highly stereoselective access to new dihydroimidazo[2,1-a]isoquinolin-3-ones 5 via intermediate N-acylisoquinolinium salts 3. Addition reactions to the enamine double bond, such as hydrogenation or epoxidation with dimethyldioxirane, leads to tetrahydroimidazo[2,1-a]isoquinoline-3-ones 6, 7 and oxiranes 8, respectively. Opening of the oxirane ring of the 8 with nucleophiles allows the synthesis of hydroxytetrahydroimidazo[2,1-a]isoquinolin-3-ones

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“…Its Lepistamides A -C (1 -3) are members of the 3,6-dioxygenated diketopiperazine family, and this type of compounds are rare in nature and mainly obtained from fungi and actinomycetes [5 -13]. Picroroccellin is the first natural substance displaying this substitution pattern [5]. Other natural compounds with this molecular skeleton were reported from Aspergillus [6] [7], Fusarium [8], Metarhizium [9], Penicillium [10] [11], Phoma [12], and Streptomyces [13].…”

mentioning

confidence: 99%

Three New 3,6‐Dioxygenated Diketopiperazines from the Basidiomycete Lepista sordida

Chen

et al. 2011

Helvetica Chimica Acta

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Three new 3,6-dioxygenated diketopiperazines, lepistamides A -C (1 -3), along with a known compound, diatretol (4), were isolated from the mycelial solid cultures of the basidiomycete Lepista sordida. Their structures were elucidated by spectroscopic means. The isolated diketopiperazines were evaluated for the cytotoxic activity against Astc-a-1, Bel 7402, and HeLa cell lines, and their biogenetic pathway was discussed.Introduction. -Recently, much attention has been paid to higher basidiomycetes because of their potential as a source of biologically active substances [1]. Lepista sordida (Schumach. ) Singer, a basidiomycetous fungus of the family Tricholomataceae, is an edible agaric species [2]. Two diterpenes (lepistal and lepistol) with the activity to induce differentiation in human leukaemia cells were previously isolated from the culture filtrate of this fungus [3]. During a screening for bioactive metabolites produced by macrofungi collected from South China, an EtOH extract from the mycelial solid cultures of a strain (GIM 5.315) of this basidiomycete showed cytotoxic activity against HeLa cells and antibacterial activity against Staphylococcus aureus. The metabolites of this fungus were therefore investigated. Three new diketopiperazines, trivially named lepistamides A -C 1 ) (1 -3), and a known one, diatretol (4) [4], were isolated from the mycelial cultures of the basidiomycete. The isolation, structure elucidation, and possible biogenetic pathway of these new compounds are described as follows.

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Pyrazine Chemistry. V. Synthesis of Methylanhydropicroroccellin and Dimethylpicroroccellin

Cited by 20 publications

References 0 publications

New diketopiperazine derivatives from a deep-sea-derived Nocardiopsis alba SCSIO 03039

New diketopiperazine derivatives from a deep-sea-derived Nocardiopsis alba SCSIO 03039

Asymmetric Synthesis of Isoquinoline Derivatives from Amino Acids

Three New 3,6‐Dioxygenated Diketopiperazines from the Basidiomycete Lepista sordida

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