- First total synthesis of eudistalbin A
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Eudistalbin A was isolated from marine tunicate eudistoma album and possess cytotoxic activity (ED50 50 value of 2.1 μmol/L using the metabolic assay MTT. All structures of new compounds were confirmed by 1H NMR, 13C NMR, HRMS and optical rotation.
- Zhang, Pu Yong,Wang, Jun Lei,Wan, Sheng Biao,Jiang, Tao
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Read Online
- Concerning the preparation of 6-bromotryptamine
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Most of the previous syntheses of the marine natural product 6-bromotryptamine have almost certainly led to partial debromination resulting in an impure product containing tryptamine. We show that loss of bromine occurs when lithium aluminum hydride is employed as a reducing agent in the final reaction step leading to 6-bromotryptamine. Reductive-debromination is also likely to intrude during some of the syntheses of 6-bromoindole, the typical precursor to 6-bromotryptamine. None of the seven described syntheses of 6-bromotryptamine that involve a reduction sequence from 6-bromoindole have reported elemental analyses as a measure of purity.
- Scott Wiens,Johnson, Jerry L.,Gribble, Gordon W.
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- Metal-Free Dearomatization: Direct Access to Spiroindol(en)ines in Batch and Continuous-Flow
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A metal-free, phosphine-catalyzed intramolecular “umpolung Michael addition” on alkynes to form spiroindol(en)ines is reported. This nucleophilic catalysis enables the formation of a wide scope of five- and six-membered spiroindol(en)ines in moderate to excellent yields in batch as well as under continuous-flow conditions. Triphenylphosphine-catalyzed nucleophilic activation of alkynes allows the exclusive formation of exo-product under mild reaction conditions.
- Ranjan, Prabhat,Ojeda, Gerardo M.,Sharma, Upendra K.,Van der Eycken, Erik V.
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supporting information
p. 2442 - 2446
(2019/01/29)
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- Synthetic Analogues of the Snail Toxin 6-Bromo-2-mercaptotryptamine Dimer (BrMT) Reveal That Lipid Bilayer Perturbation Does Not Underlie Its Modulation of Voltage-Gated Potassium Channels
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Drugs do not act solely by canonical ligand-receptor binding interactions. Amphiphilic drugs partition into membranes, thereby perturbing bulk lipid bilayer properties and possibly altering the function of membrane proteins. Distinguishing membrane perturbation from more direct protein-ligand interactions is an ongoing challenge in chemical biology. Herein, we present one strategy for doing so, using dimeric 6-bromo-2-mercaptotryptamine (BrMT) and synthetic analogues. BrMT is a chemically unstable marine snail toxin that has unique effects on voltage-gated K+ channel proteins, making it an attractive medicinal chemistry lead. BrMT is amphiphilic and perturbs lipid bilayers, raising the question of whether its action against K+ channels is merely a manifestation of membrane perturbation. To determine whether medicinal chemistry approaches to improve BrMT might be viable, we synthesized BrMT and 11 analogues and determined their activities in parallel assays measuring K+ channel activity and lipid bilayer properties. Structure-activity relationships were determined for modulation of the Kv1.4 channel, bilayer partitioning, and bilayer perturbation. Neither membrane partitioning nor bilayer perturbation correlates with K+ channel modulation. We conclude that BrMT's membrane interactions are not critical for its inhibition of Kv1.4 activation. Further, we found that alkyl or ether linkages can replace the chemically labile disulfide bond in the BrMT pharmacophore, and we identified additional regions of the scaffold that are amenable to chemical modification. Our work demonstrates a strategy for determining if drugs act by specific interactions or bilayer-dependent mechanisms, and chemically stable modulators of Kv1 channels are reported.
- Dockendorff, Chris,Gandhi, Disha M.,Kimball, Ian H.,Eum, Kenneth S.,Rusinova, Radda,Ingólfsson, Helgi I.,Kapoor, Ruchi,Peyear, Thasin,Dodge, Matthew W.,Martin, Stephen F.,Aldrich, Richard W.,Andersen, Olaf S.,Sack, Jon T.
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p. 2733 - 2743
(2018/05/23)
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- An environmentally friendly protocol for oxidative halocyclization of tryptamine and tryptophol derivatives
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An environmentally friendly and efficient protocol (KX/oxone) for oxidative halocyclization of tryptamine/tryptophol derivatives was developed and demonstrated with 28 examples and concise total synthesis of cyclotryptamine alkaloid protubonines A and B. The distinct advantage of this protocol over all previous methods is that no organic byproduct is generated from a halogenating agent or oxidant, thus greatly reducing the environmental impact of halocyclization and facilitating the post-reaction purification.
- Xu, Jun,Tong, Rongbiao
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supporting information
p. 2952 - 2956
(2017/07/24)
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- Marine AChE inhibitors isolated from Geodia barretti: Natural compounds and their synthetic analogs
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Barettin, 8,9-dihydrobarettin, bromoconicamin and a novel brominated marine indole were isolated from the boreal sponge Geodia barretti collected off the Norwegian coast. The compounds were evaluated as inhibitors of electric eel acetylcholinesterase. Barettin and 8,9-dihydrobarettin displayed significant inhibition of the enzyme, with inhibition constants (Ki) of 29 and 19 μM respectively towards acetylcholinesterase via a reversible noncompetitive mechanism. These activities are comparable to those of several other natural acetylcholinesterase inhibitors of marine origin. Bromoconicamin was less potent against acetylcholinesterase, and the novel compound was inactive. Based on the inhibitory activity, a library of 22 simplified synthetic analogs was designed and prepared to probe the role of the brominated indole, common to all the isolated compounds. From the structure-activity investigation it was shown that the brominated indole motif is not sufficient to generate a high acetylcholinesterase inhibitory activity, even when combined with natural cationic ligands for the acetylcholinesterase active site. The four natural compounds were also analysed for their butyrylcholinesterase inhibitory activity in addition and shown to display comparable activities. The study illustrates how both barettin and 8,9-dihydrobarettin display additional bioactivities which may help to explain their biological role in the producing organism. The findings also provide new insights into the structure-activity relationship of both natural and synthetic acetylcholinesterase inhibitors.
- Olsen, Elisabeth K.,Hansen, Espen,Moodie, Lindon W. K.,Isaksson, Johan,Sep?i?, Kristina,Cergolj, Marija,Svenson, Johan,Andersen, Jeanette H.
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p. 1629 - 1640
(2016/02/09)
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- BIS-INDOLE ALKALOIDS FOR USE IN THE TREATMENT OF INFECTIONS
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The present application describes bisindole alkaloids of formulas I and II and pharmaceutical compositions thereof useful in the treatment of bacterial infection such as Staphylococcus aureus (MRSA) infection: wherein X1 is: wherein X2 is:
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Page/Page column 27; 28; 30
(2016/02/29)
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- Chiral anion phase transfer of aryldiazonium cations: An enantioselective synthesis of C3-diazenated pyrroloindolines
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Herein is reported the first asymmetric utilization of aryldiazonium cations as a source of electrophilic nitrogen. This is achieved through a chiral anion phase-transfer pyrroloindolinization reaction that forms C3-diazenated pyrroloindolines from simple tryptamines and aryldiazonium tetrafluoroborates. The title compounds are obtained in up to 99% yield and 96% ee. The air- and water-tolerant reaction allows electronic and steric diversity of the aryldiazonium electrophile and the tryptamine core. Live and let diazene: Chiral anion phase transfer of aryldiazonium cations has been utilized to prepare C3-diazenated pyrroloindolines. The air- and water-tolerant reaction allows electronic and steric diversity in the aryldiazonium electrophile and the tryptamine core, with the products being obtained in up to 99% yield and 96% ee (MTBE=methyl tert-butyl ether).
- Nelson, Hosea M.,Reisberg, Solomon H.,Shunatona, Hunter P.,Patel, Jigar S.,Toste, F. Dean
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supporting information
p. 5600 - 5603
(2014/06/10)
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- Enantioselective total synthesis of eudistomidins G, H, and I
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Asymmetric first total synthesis of eudistomidins G, H, and I, tetrahydro-β-carboline alkaloids from the Okinawan marine tunicate Eudistoma glaucus, has been accomplished with the Bischler-Napieralski reaction and the Noyori catalytic asymmetric hydrogen-transfer reaction. The absolute configurations of eudistomidins G, H, and I were confirmed from comparison of the 1H and 13C NMR, and CD spectral data of synthetic and natural eudistomidins G, H, and I, respectively.
- Ishiyama, Haruaki,Yoshizawa, Kazuaki,Kobayashi, Jun'ichi
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experimental part
p. 6186 - 6192
(2012/08/27)
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