- Palladium-catalyzed intramolecular α-arylation of aliphatic ketone, formyl, and nitro groups
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Intramolecular arylation of properly designed substrates bearing a ketone, formyl, or nitro terminating group was achieved by use of a PdCl 2(Ph3P)2-Cs2CO3 reaction system to form a variety of carbocyclic compounds. Arylation in ketone compounds afforded benzene-annulated bridged or spirocycloalkanone derivatives, depending on the structure of the cyclization precursors. Arylation in formyl compounds occurred at the α-position (α-arylation) or at the carbonyl carbon (carbonyl-arylation) depending on the structure of the cyclization precursors and on the reaction solvent. An α-arylated secondary nitro group was partially transformed to ketone in the manner of the Nef reaction, whereas a tertiary nitro group was partially eliminated to afford a styrene-type olefin. Graphical Abstract
- Muratake, Hideaki,Natsume, Mitsutaka,Nakai, Hiroshi
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p. 11783 - 11803
(2007/10/03)
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- Cyclization of aryllithiums tethered to methylenecycloalkanes: Stereoselective synthesis of 4α-substituted cis-hexahydrofluorenes
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The cyclization of an aryllithium tethered to a methylenecycloalkane, generated from 2-(o-bromobenzyl)-1-methylenecycloalkanes 1, 2, and 3 by low-temperature lithium-bromine exchange, has been found to be a kinetically slow but thermodynamically favorable process that proceeds at a convenient rate in an exclusively 5-exo fashion when solutions of the aryllithium in n-heptane-di-n-butyl ether (9:1 v/v) are warmed to 45 °C. The cyclization affords stereoisomerically pure cisfused products (7 and 8) when the methylenecycloalkane is five- or six-membered but it is less stereoselective when the methylenecycloalkane is seven-membered. The ring-closure of the aryllithium derived from 2-(o-bromobenzyl)-1-methylenecyclohexane (2) provides an experimentally convenient route to stereoisomerically pure 4a-substituted cis-hexahydrofluorenes in 60-90% isolated yield.
- Bailey, William F.,Daskapan, Tahir,Rampalli, Sriram
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p. 1334 - 1338
(2007/10/03)
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- A Novel Palladium-Catalyzed Intramolecular Redox Reaction
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matrix presented A new type of palladium-catalyzed redox reaction is described, forming enones from 2-(2-bromobenzyl)-ketones with an overall loss of HBr. The scope and limitations of the reaction are demonstrated by a series of cyclic and acyclic substra
- Hoegenauer, Klemens,Mulzer, Johann
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p. 1495 - 1497
(2007/10/03)
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- Regiochemistry in aryl radical cyclization onto methylenecycloalkanes
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Bu3SnH-mediated aryl radical cyclization onto methylenecycloalkanes having a phenylthio, an ester, or a nitrile group at the terminus of the alkenic bond provides exclusively exo cyclization products. The results are in sharp contrast to those reported for nonsubstituted methylenecycloalkanes, which give exclusively endo cyclization products. Formation of endo cyclization products has been suggested to be a result of a consecutive 5-exo cyclization of an aryl radical and neophyl rearrangement. The exo-selective aryl radical cyclization offers a new method for synthesizing fused aromatic compounds containing a benzylic quaternary carbon atom.
- Ishibashi,Kobayashi,Nakashima,Tamura
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p. 9022 - 9027
(2007/10/03)
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- Efficient synthesis of 2- and 3-substituted indenes from 2-bromobenzyl bromide through an enolate alkylation/Cr(II)/Ni(II)-mediated carbonyl addition sequence
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An efficient new synthesis of 2- and 3-substituted indenes has been developed based on the nickel-catalyzed chromium(II)-promoted addition of aryl bromides to a tethered ketone carbonyl. Several tethered bromoaryl ketones were prepared through enolate alk
- Halterman, Ronald L.,Zhu, Chengian
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p. 7445 - 7448
(2007/10/03)
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- Regioselective Aryl Radical Cyclization. 1. Stereocontrolled Synthesis of Linearly Condensed Hydroaromatic Carbocyclic Systems through 6-endo-ring Closures
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The stereocontrolled synthesis of trans-octahydroanthracenes 3, 11a-c, and 14a-c and trans-octahydro-5aH-cycloheptanaphthalene (27) through implementation of an efficient and highly regioselective 6-endo-trig-aryl radical cyclization of the respective 2-(o-bromoaryl)-1-methylenecyclohexanes 2, 10a-c, and 13a-c and 2-(o-bromobenzyl)-1-methylenecycloheptane (41) with tri-n-butyltin hydride id described.The radical cyclization of 2-(o-bromobenzyl)-1-methylenecyclopentane (43), in contrast, produced a mixture of the cis- and trans-hexahydro-1H-benzindenes (38) and (37).
- Pal, Sitaram,Mukhopadhyaya, Jayanta K.,Ghatak, Usha Ranjan
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p. 2687 - 2694
(2007/10/02)
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- Synthesis and Pharmacological Evaluation of Hexahydrofluorenamines as Noncompetitive Antagonists at the N-Methyl-D-aspartate Receptor
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The noncompetitive (PCP) site of the N-methyl-D-aspartate (NMDA) receptor complex has been implicated in a number of pathologies, including the etiology of ischemic stroke.Recent testing has shown that cis-1,2,3,4,9,9a-hexahydro-N-methyl-4aH-fluoren-4a-am
- Hays, Sheryl J.,Novak, Perry M.,Ortwine, Daniel F.,Bigge, Christopher F.,Colbry, Norman L.,et al.
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p. 654 - 670
(2007/10/02)
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- Polycyclic amines useful as cerebrovascular agents
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A novel series of polycyclic amines, derivatives, methods of making the compounds, novel intermediates, compositions containing them, and methods for using them in the treatment and prevention of cerebrovascular disorders are disclosed.
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