- Total syntheses of oroidin, hymenidin and clathrodin
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The total syntheses of oroidin, hymenidin and clathrodin are reported via the intermediacy of an imidazo[1,2-a]pyrimidine derivative. The chemistry described herein obviates the need for expensive guanidine reagents, multiply protected prefunctionalized 2-aminoimidazole synthons, or the need for laborious olefinations thereby achieving synthetic efficiency amenable to scale-up. The approach outlined in this manuscript provides an opportunity for further functionalizations through the imidazo[1,2-a]pyrimidine core and through functional groups placed strategically on the side chain.
- Rasapalli, Sivappa,Kumbam, Venkatreddy,Dhawane, Abasaheb N.,Golen, James A.,Lovely, Carl J.,Rheingold, Arnold L.
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- Synthesis of Marine Sponge Alkaloids Oroidin, Clathrodin, and Dispacamides. Preparation and Transformation of 2-Amino-4,5-dialkoxy-4,5-dihydroimidazolines from 2-Aminoimidazoles
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The preparation and transformation of 2-amino-4,5-dialkoxy-4,5-dihydroimidazolines A from 2-aminoimidazoles (AIs) is described. The oxidation of 2-aminoimidazole 8 with NCS in methanol affords cyclic guanidine adduct 9 which, upon heating, affords vinylogous AI derivative 3 and 2-aminoimidazolinone (glycocyamidine) 13. Olefin 3 comprises the core structure found in the oroidin alkaloids. Furthermore, oxidation of 8 with Br2 and DMSO affords directly α,β-unsaturated imidazolinone 14 which is the key structural unit comprising the dispacamides (2). A highly facile and practical synthesis of the C11N5 marine sponge alkaloids oroidin (1a), clathrodin (1c), and dispcamides (2) is outlined.
- Olofson, Anne,Yakushijin, Kenichi,Horne, David A.
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- Clathrodin, hymenidin and oroidin, and their synthetic analogues as inhibitors of the voltage-gated potassium channels
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We have prepared three alkaloids from the Agelas sponges, clathrodin, hymenidin and oroidin, and a series of their synthetic analogues, and evaluated their inhibitory effect against six isoforms of the Kv1 subfamily of voltage-gated potassium channels, Kv1.1-Kv1.6, expressed in Chinese Hamster ovary (CHO) cells using automated patch clamp electrophysiology assay. The most potent inhibitor was the (E)-N-(3-(2-amino-1H-imidazol-4-yl)allyl)-4,5-dichloro-1H-pyrrole-2-carboxamide (6g) with IC50 values between 1.4 and 6.1 μM against Kv1.3, Kv1.4, Kv1.5 and Kv1.6 channels. All compounds tested displayed selectivity against Kv1.1 and Kv1.2 channels. For confirmation of their activity and selectivity, compounds were additionally evaluated in the second independent system against Kv1.1-Kv1.6 and Kv10.1 channels expressed in Xenopus laevis oocytes under voltage clamp conditions where IC50 values against Kv1.3-Kv1.6 channels for the most active analogues (e.g. 6g) were lower than 1 μM. Because of the observed low sub-micromolar IC50 values and fairly low molecular weights, the prepared compounds represent good starting points for further optimisation towards more potent and selective voltage-gated potassium channel inhibitors.
- Zidar, Nace,?ula, Ale?,Toma?i?, Tihomir,Rogers, Marc,Kirby, Robert W.,Tytgat, Jan,Peigneur, Steve,Kikelj, Danijel,Ila?, Janez,Ma?i?, Lucija Peterlin
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p. 232 - 241
(2017/08/14)
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- A convenient strategy for synthesizing the Agelas alkaloids clathrodin, oroidin, and hymenidin and their (un)saturated linker analogs
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A convenient strategy for the scalable synthesis of the 2-aminoimidazole alkaloids, clathrodin, oroidin, and hymenidin derived from marine Agelas species and their analogs possessing a saturated or unsaturated linker moiety is described. The key intermediates, 4-(3-aminopropyl)-1H-imidazol-2-amine and (E)-4-(3-aminoprop-1-en-1-yl)-1H-imidazol-2-amine were obtained through two different synthetic pathways starting from l-ornithine and benzyl 1,2-dihydropyridine-1-carboxylate respectively, using (i) an innovative combination of Weinreb amide strategy with di-Boc protection, and (ii) a modified pyridine-1(2H)-carboxylate based strategy. Convenient access to these 2-aminoimidazole amines is crucial for the synthesis of libraries of clathrodin, oroidin, and hymenidin analogs.
- ?ula, Ale?,Kikelj, Danijel,Ila?, Janez
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p. 3999 - 4001
(2014/07/08)
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- Antimicrobial activity of the marine alkaloids, clathrodin and oroidin, and their synthetic analogues
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Marine organisms produce secondary metabolites that may be valuable for the development of novel drug leads as such and can also provide structural scaffolds for the design and synthesis of novel bioactive compounds. The marine alkaloids, clathrodin and oroidin, which were originally isolated from sponges of the genus, Agelas, were prepared and evaluated for their antimicrobial activity against three bacterial strains (Enterococcus faecalis, Staphylococcus aureus and Escherichia coli) and one fungal strain (Candida albicans), and oroidin was found to possess promising Gram-positive antibacterial activity. Using oroidin as a scaffold, 34 new analogues were designed, prepared and screened for their antimicrobial properties. Of these compounds, 12 exhibited >80% inhibition of the growth of at least one microorganism at a concentration of 50 μM. The most active derivative was found to be 4-phenyl-2-aminoimidazole 6h, which exhibited MIC90 (minimum inhibitory concentration) values of 12.5 μM against the Gram-positive bacteria and 50 μM against E. coli. The selectivity index between S. aureus and mammalian cells, which is important to consider in the evaluation of a compound's potential as an antimicrobial lead, was found to be 2.9 for compound 6h.
- Zidar, Nace,Montalv?o, Sofia,Hodnik, ?iga,Nawrot, Dorota A.,?ula, Ale?,Ila?, Janez,Kikelj, Danijel,Tammela, P?ivi,Ma?i?, Lucija Peterlin
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p. 940 - 963
(2014/03/21)
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- A novel synthesis of the 2-amino-1H-imidazol-4-carbaldehyde derivatives and its application to the efficient synthesis of 2-aminoimidazole alkaloids, oroidin, hymenidin, dispacamide, monobromodispacamide, and ageladine A
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A novel synthesis of 2-amino-1H-imidazol-4-carbaldehyde derivatives was achieved by the reaction of tert-butoxycarbonylguanidine with 3-bromo-1,1-dimethoxypropan-2-one as a key step. The usefulness of the derivatives as building blocks was proved by accomplishing the efficient synthesis of the representative 2-aminoimidazole alkaloids, oroidin, hymenidin, dispacamide, monobromodispacamide, and ageladine A.
- Ando, Naoki,Terashima, Shiro
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experimental part
p. 6224 - 6237
(2010/09/11)
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- Direct access to marine pyrrole-2-aminoimidazoles, oroidin, and derivatives, via new acyl-1,2-dihydropyridin intermediates
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A short synthesis of the C11N5 oroidin derivatives is reported. The key step of the strategy is a one-pot oxidative bromine-mediated addition of protected guanidines to the N-acyl-1,2-dihydropyridines 9a-c. The new N-acyl-1,2-dihydropyridines were prepared directly from pyridine and pyrrole-2-carbonyl chloride by reduction with borohydride reagent in one step.
- Schroif-Gregoire, Cosima,Travert, Nathalie,Zaparucha, Anne,Al-Mourabit, Ali
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p. 2961 - 2964
(2007/10/03)
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- A novel synthesis of the 2-aminoimidazol-4-carbaldehyde derivatives, versatile synthetic intermediates for 2-aminoimidazole alkaloids
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The title synthesis was achieved by the reaction of t- butoxycarbonylguanidine with 3-bromo-1,1-dimethoxypropan-2-one as a key step. Starting with 1-tert-butoxycarbonyl-2-tert-butoxycarbonylaminoimidazol-4- carbaldehyde thus obtained expeditious synthesis of oroidin, hymenidin, dispacamide and monobromodispacamide, the representative 2-aminoimidazole alkaloids, was accomplished. Georg Thieme Verlag Stuttgart.
- Ando, Naoki,Terashima, Shiro
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p. 2836 - 2840
(2008/02/13)
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- Synthesis of the marine sponge alkaloid oroidin and its analogues via Suzuki cross-coupling reactions
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A new synthesis of the natural product oroidin was described using a Suzuki coupling reaction as key step. This method was extended to the synthesis of various analogues of oroidin and hymenidin.
- Berrée, Fabienne,Girard-Le Bleis, Pascale,Carboni, Bertrand
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p. 4935 - 4938
(2007/10/03)
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- Synthesis of marine 2-aminoimidazole metabolites: Hymenidin, oroidin and keramadine
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Through a general synthetic scheme, hymenidin, oroidin and keramadine, all marine 2-aminoimidazole metabolites were prepared. Seven steps from imidazolemethanol provided an improved synthesis of oroidin and the first synthesis of hymenidin and keramadine.
- Daninos-Zeghal, Sophie,Al Mourabit, Ali,Ahond, Alain,Poupat, Christiane,Potier, Pierre
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p. 7605 - 7614
(2007/10/03)
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- A Simple and Practical Synthesis of 2-Aminoimidazoles
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A new and simple two-step procedure to synthesize 2-aminoimidazoles (2-AI's) from readily available materials has been developed.The cyclization reaction of α-halo ketones and N-acetylguanidine in acetonitrile (MeCN) at reflux, or in dimethylformamide (DMF) at ambient temperature, gives 4(5)-substituted and 4,5-disubstituted N-(1H-imidazol-2-yl)acetamides, which are then hydrolyzed to their respective 2-AI's.In general, the purified products were isolated in good yields.We have prepared several examples and have demonstrated the usefulness of this method by its application in the total synthesis of 8, an interesting histamine analog, and oroidin, 15, a marine natural product isolated from various sponges.
- Little, Thomas L.,Webber, Stephen E.
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p. 7299 - 7305
(2007/10/02)
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