- Total syntheses of (±)-cis-trikentrin A and (±)-cis- trikentrin B via electrocyclic ring closures of 2,3-divinylpyrrolines
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A convergent and versatile strategy for the diastereoselective syntheses of (±)-cis-trikentrin A and B in 10 and 12 steps, respectively, from commercially available N-BOC-2-pyrrolidinone is described. The key step in each of the total syntheses is the construction of the central benzene ring via a facile 6π-electrocyclic ring closure of an appropriately substituted 2,3-divinylpyrroline, in turn, readily available by a Stille coupling reaction.
- Huntley, Raymond J.,Funk, Raymond L.
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- Total synthesis of (±)-herbindole A, (±)-herbindole B, and (±)-cis-trikentrin A
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(Chemical Equation Presented) Herein we describe a divergent total synthesis of the title compounds utilizing Diels-Alder reactions of monoimine quinoids, followed by cyclization of the aromatized adducts to generate the tricyclic skeletons. Elaboration t
- Jackson, Stephen K.,Kerr, Michael A.
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- Asymmetric hydrovinylation of vinylindoles. A facile route to cyclopenta[g]indole natural products (+)-cis-trikentrin A and (+)-cis-trikentrin B
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Vinylindoles undergo Ni(II)-catalyzed asymmetric hydrovinylation under very mild conditions (-78 °C, 1 atm ethylene, 4 mol % catalyst) to give the corresponding 2-but-3-enyl derivatives in excellent yields and enantioselectivities. Hydroboration of the alkene and oxidation to an acid, followed by Friedel-Crafts annulation, gives an indole-annulated cyclopentanone that is a suitable precursor for the syntheses of cis-trikentrins and all known herbindoles. For example, the cyclopentanone from 4-ethyl-7-vinylindole is converted into (+)-cis-trikentin A in four steps (Wittig reaction, alkene isomerization, diastereoselective hydrogenation, and nitrogen deprotection). The previous synthesis of this molecule from (S)-(-)-malic acid involved more than 20 steps and a preparative HPLC separation of diastereomeric intermediates.
- Liu, Wang,Lim, Hwan Jung,Rajanbabu
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p. 5496 - 5499
(2012/05/20)
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- A diastereoselective total synthesis of trans-trikentrin A: A ring contraction approach
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(Chemical Equation Presented) A new route to obtain the polyalkylated indole (±)-trans-trikentrin A was developed. The synthesis of this natural alkaloid features a thallium(III)-mediated ring contraction reaction to obtain the trans-1,3-disubstituted five-membered ring in a diastereoselective manner. Thallium(III) is chemoselective in this rearrangement, reacting with the olefin without oxidation of the indole moiety. Other key transformations are the Bartoli's reaction to construct the heterocyclic ring and a Heck coupling to add the carbons atom that will originate the nonaromatic cycle.
- Silva Jr., Luiz F.,Craveiro, Marcus V.
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supporting information; experimental part
p. 5417 - 5420
(2009/06/06)
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- Total Synthesis of (+/-)-cis-Trikentrin A
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Two patways towards the construction of the trikentrin skeleton are presented, one leading to the total synthesis of (+/-)-cis-Trikentrin A (1).The key step is the intramolecular Heck coupling of the triflate 21 to form the five-membered ring of the indenes 22 and 23.
- Wiedenau, Paul,Monse, Barbara,Blechert, Siegfried
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p. 1167 - 1176
(2007/10/02)
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- Preparation of alkyl-substituted indoles in the benzene portion. Part 11. Total synthesis of (6R,8S)-herbindole A, (6R,8S)-herbindole B, (6R,8S)-herbindole C (6R,8S)-cis-trikentrin A, (6R,8S)-cis-trikentrin B, (6R,8R)-trans-trikentrin B, and (6R,8R)-iso-t
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The key intermediate, (3R,5S)-3,5-dimethyl-1-cyclopentenylmethanol (13) for chiral syntheses of herbindoles and trikentrins, was prepared from the known Diels-Alder adduct 12. Employing pertinent methodologies developed in the previous model study (preced
- Muratake,Mikawa,Seino,Natsume
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p. 854 - 864
(2007/10/02)
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- Total Synthesis of (±)-cis- And (±)-trans-Trikentrin A: Diels-Alder Reactions of Heteroaromatic Azadienes
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A five-step total synthesis of cis- and trans-trikentrin A is detailed and is based on the implementation of two sequential heteroaromatic azadiene Diels-Alder reactions constituting a general approach to the preparation of substituted indoles.
- Boger, Dale L.,Zhang, Minsheng
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p. 4230 - 4234
(2007/10/02)
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- SYNTHESIS OF (+/-)- AND (-)-CIS-TRIKENTRIN A, (+/-)- AND (-)-TRANS-TRIKENTRIN A, (+/-)-CIS-TRIKENTRIN B, (+/-)-TRANS-TRIKENTRIN B, AND (+/-)-ISO-TRANS-TRIKENTRIN B
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Synthesis of the titled indole alkaloids from a marine source was accomplished according to the general scheme in Chart 1.The key steps were preparation of suitably substituted β-hydroxyl carbonyl compounds (8b) from 7b, and the subsequent indole cyclizat
- Muratake, Hideaki,Watanabe, Makoto,Goto, Koichi,Natsume, Mitsutaka
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p. 4179 - 4192
(2007/10/02)
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- The Total Synthesis of (+/-)-cis- and trans-Trikentrin A
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The synthesis of the title compounds, which are novel cyclopentindoles isolated from a marine sponge Trikentrion flabelliforme, is described.An aryl radical cyclization and a 1,5-electrocyclic reaction of a nitrene are key steps in formation of the two
- MacLeod, John K.,Monahan, Lilian C.
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p. 329 - 337
(2007/10/02)
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- THE SYNTHESIS OF (+/-)CIS-TRIKENTRINA
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The synthesis of a novel sponge metabolite is described, utilising an aryl radical cyclisation to form the substituted indane system.
- Macleod, John K.,Monahan, Lilian C.
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p. 391 - 392
(2007/10/02)
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