- THE TOTAL SYNTHESIS OF PIPTOSIDIN
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The synthesis of piptosidin, 2a, by the Michael addition of ascorbic acid to tigloyl cyanide is reported.
- Poss, A. J.,Smyth, M. S.
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- Miniolins A-C, novel isomeric furanones induced by epigenetic manipulation of Penicillium minioluteum
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Cultivation of Penicillium minioluteum with azacitidine, a DNA methyltransferase inhibitor, led to the isolation of a novel type of aspertetronin dimer, named miniolins A-C (1-3), along with their precursor aspertetronin A (4). The structures of 1-3 were elucidated by extensive spectroscopic methods, and the absolute configurations were assigned by the chiral HPLC analysis of chemical degradation products and electronic circular dichroism associated with the TDDFT computational method (CAM-B3LYP/TZVP). The miniolins showed moderate cytotoxic activity against Hela cell lines. This journal is
- Tang, Hao-Yu,Zhang, Qiang,Gao, Yu-Qi,Zhang, An-Ling,Gao, Jin-Ming
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- Rapid and Efficient Isolation of the Nicotinic Receptor Antagonist Methyllycaconitine from Delphinium: Assignment of the Methylsuccinimide Absolute Stereochemistry as S
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Methyllycaconitine (MLA) has been isolated from Garden Hybrid Delphinium and purified by vacuum liquid chromatography. 13C NMR and optical rotation has been used to characterize the absolute configuration of the methylsuccinimide moiety as S.Ligand binding assays confirmed the potency of MLA and its selectivity for α-bungarotoxin-sensitive neuronal nicotinic acetylcholine receptors.
- Coates, Philippa A.,Blagbrough, Ian S.,Hardick, David J.,Rowan, Michael G.,Wonnacott, Susan,Potter, Barry V. L.
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- Aspernigrins with anti-HIV-1 activities from the marine-derived fungus Aspergillus Niger SCSIO Jcsw6F30
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Two new 2-benzylpyridin-4-one containing metabolites, aspernigrins C (3) and D (4), together with six known compounds (1, 2, and 5-8), were isolated from the marine-derived fungus Aspergillus Niger SCSIO Jcsw6F30. The structures of the new compounds were determined by NMR, MS, and optical rotation analyses. All the isolated compounds were evaluated for their inhibitory activities against infection with HIV-1 SF162 in TZM-bl cells. Malformin C (5) showed the strongest anti-HIV-1 activity with IC50 of 1.4 ± 0.06 μM (selectivity index, 11.4), meanwhile aspernigrin C (3) also exhibited potent activity with IC50 of 4.7 ± 0.4 μM (selectivity index, 7.5).
- Zhou, Xuefeng,Fang, Wei,Tan, Suiyi,Lin, Xiuping,Xun, Tianrong,Yang, Bingjie,Liu, Shuwen,Liu, Yonghong
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- Preparation of Both Enantiomers of Malic and Citramalic Acid and Other Hydroxysuccinic Acid Derivatives by Stereospecific Hydrations of cis or trans 2-Butene-1,4-dioic Acids with Resting Cells of Clostridium formicoaceticum
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(R)-Malic, (S)-malic, (R)-citramalic, (S)-citramalic, (2R,3S)-2-hydroxy-3-methylsuccinic and (2R,3S)-2,3-dimethyl-2-hydroxysuccinic acid were prepared on scales up to 25 mmol by stereospecific addition of water to different 2-butene-1,4-dioic acid derivatives catalyzed by resting cells of Clostridium formicoaceticum (Scheme 1).The (3R)-monodeuterio (R)- and (S)-malic acid as well as (R)- and (S)-citramalic acid were prepared using freeze-dried cells in 2H2O-buffer.The stereochemical purity of the products was in most cases >/= 99percent.
- Eck, Richard,Simon, Helmut
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- Tubulysin Synthesis Featuring Stereoselective Catalysis and Highly Convergent Multicomponent Assembly
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A concise and modular total synthesis of the highly potent N14-desacetoxytubulysin H (1) has been accomplished in 18 steps in an overall yield of up to 30percent. Our work highlights the complexity-augmenting and route-shortening power of diastereoselective multicomponent reaction (MCR) as well as the role of bulky ligands to perfectly control both the regioselective and diastereoselective synthesis of tubuphenylalanine in just two steps. The total synthesis not only provides an operationally simple and step economy but will also stimulate major advances in the development of new tubulysin analogues.
- Vishwanatha, Thimmalapura M.,Giepmans, Ben,Goda, Sayed K.,D?mling, Alexander
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p. 5396 - 5400
(2020/07/08)
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- Enantiospecific C-H Activation Using Ruthenium Nanocatalysts
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The activation of C-H bonds has revolutionized modern synthetic chemistry. However, no general strategy for enantiospecific C-H activation has been developed to date. We herein report an enantiospecific C-H activation reaction followed by deuterium incorporation at stereogenic centers. Mechanistic studies suggest that the selectivity for the α-position of the directing heteroatom results from a four-membered dimetallacycle as the key intermediate. This work paves the way to novel molecular chemistry on nanoparticles.
- Taglang, Céline,Martínez-Prieto, Luis Miguel,Del Rosal, Iker,Maron, Laurent,Poteau, Romuald,Philippot, Karine,Chaudret, Bruno,Perato, Serge,Sam Lone, Ana?s,Puente, Céline,Dugave, Christophe,Rousseau, Bernard,Pieters, Grégory
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supporting information
p. 10474 - 10477
(2015/09/02)
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