- Synthetic studies towards the Lycopodium alkaloid paniculatine
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Two bridging tetracyclic products have been observed while attempting to construct the final C-ring of the Lycopodium alkaloid, paniculatine, by an intramolecular addition of enolates to unactivated N-alkyl pyridinium salts. The Royal Society of Chemistry 2013.
- Lei, Shenghui
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p. 11014 - 11020
(2013/09/02)
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- Total synthesis of (+)-nankakurines A and B and (±)-5-epi- nankakurine A
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The first total syntheses of the Lycopodium alkaloids (+)-nankakurine A (2), (+)-nankakurine B (3), and the originally purported structure 1 of nankakurine A were accomplished. The syntheses of 2 and 3 feature a demanding intramolecular azomethine imine cycloaddition as the key step for generating the octahydro-3,5-ethanoquinoline moiety and installing the correct relative configuration at the spiropiperidine ring juncture. The cyclization precursor was prepared from octahydronaphthalene ketone 50, which was assembled from enone (+)-9 and diene 48 by a cationic Diels-Alder reaction. The Diels-Alder reactants were synthesized from 5-hexyn-1-ol (16) and (+)-pulegone (49), respectively. The tetracyclic ring system of 1 was generated using an unprecedented nitrogen-terminated aza-Prins cyclization cascade. The enantioselective total syntheses of (+)-nankakurine A (2) and (+)-nankakurine B (3) establish the relative and absolute configuration of these alkaloids and are sufficiently concise that substantial quantities of 2 and 3 were prepared for biological studies. (+)-Nankakurine A and (+)-nankakurine B showed no effect on neurite outgrowth in rat hippocampal H-19 cells over a concentration range of 0.3-10 μM.
- Altman, Ryan A.,Nilsson, Bradley L.,Overman, Larry E.,Read De Alaniz, Javier,Rohde, Jason M.,Taupin, Veronique
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experimental part
p. 7519 - 7534
(2011/02/23)
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- Synthesis of chiloglottones - Semiochemicals from sexually deceptive orchids and their pollinators
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A five-step synthesis of monoalkyl- and 2,5-dialkyl-1,3-cyclohexanediones (1) is described via a sequence involving sequential Birch reductions and alkylations from the readily accessible and inexpensive starting material, 3,5-dimethoxybenzoic acid. Two approaches were considered in which alkylation at C-2 occurs either prior or subsequent to the proposed reduction. The successful route, in which Birch reduction of a 3-alkyl resorcinol derivative (3) precedes alkylation was applied in the synthesis of chiloglottone 1 (1dc), in 58% overall yield. Chiloglottone 1 is a member of a new class of natural products, representing a known sex pheromone of the thynnine wasp Neozeleboria cryptoides and pollinator attractant in the Australian sexually deceptive orchid genus Chiloglottis. The synthetic homologues were assessed for their biological activity via electroantennographic detection.
- Poldy, Jacqueline,Peakall, Rod,Barrow, Russell Allan
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supporting information; experimental part
p. 4296 - 4300
(2009/12/06)
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- Synthesis of substituted quinazolines
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A novel and flexible synthetic route is described for the synthesis of 5,6,8-alkyl-7-methoxy-2-aminoquinazolines using dihydrobenzenes as key intermediates.
- Bathini, Yadagiri,Sidhu, Inderjit,Singh, Rajeshwar,Micetich, Ronald G.,Toogood, Peter L.
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p. 3295 - 3296
(2007/10/03)
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- Synthesis of 4,4-Disubstituted Cyclohexenones. Part 2. Cycloaddition of 2-Chloroacrylonitrile to 5-Substituted 1,3-Dimethoxycyclohexa-1,4-dienes
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The cycloaddition of 2-chloroacrylonitrile to 1,3-dimethoxycyclohexadienes (3; R1=OMe, R2=H), derived by in situ conjugation of the Birch reduction products (12) produced from aromatic precursors (11) gave after acid work-up mainly bicyclooctanone
- Clark, Richard S. J.,Holmes, Andrew B.,Matassa, Victor G.
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p. 1389 - 1400
(2007/10/02)
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- A GENERAL SYNTHETIC METHOD FOR PRENYLATED PHENOLS OF MICROBIAL ORIGIN
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Prenylated phenols with a fully substituted benzene ring, such as colletochlorins A and B, were synthesized by first prenylating 1,5-dimethoxy-3-methyl-1,4-cyclohexadiene and then effecting the aromatization of the prenylated product.
- Mori, Kenji,Sato, Kazuo
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p. 1221 - 1225
(2007/10/02)
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