- Bis(cyclopropenium)phosphines: Synthesis, Reactivity, and Applications
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A straightforward route for the preparation of a set of bis(cyclopropenium)-substituted phosphines is reported. Due to their dicationic nature, these ligands depict an excellent π-acceptor character. The effect of the ligand substituent pattern on the catalytic activity of the metal complexes thereof derived is also studied. Whereas sterically demanding biaryl groups directly attached to the phosphorus atom seem to facilitate elementary steps such as the product release from the catalyst, long chain dialkylamino groups on the cyclopropenium units maximize the catalysts solubility and, thus, allow the use of typical apolar solvents such as toluene. Importantly, all new ligands prepared can be easily handled in air. Finally, the impact of the newly prepared dicationic phosphines in hydroarylation reactions is demonstrated. In particular, their use in the synthesis of several naphtho[1,2-b]furanes and naturally occurring naphthalene derivatives such as Calanquinone C is reported.
- Mehler, Gerlinde,Linowski, Pawel,Carreras, Javier,Zanardi, Alessandro,Dube, Jonathan W.,Alcarazo, Manuel
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supporting information
p. 15320 - 15327
(2016/10/13)
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- Zeolite-catalyzed synthesis of 2,3-unsubstituted benzo[b]furans via the intramolecular cyclization of 2-aryloxyacetaldehyde acetals
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An efficient and environmentally benign heterogeneous catalytic process for the synthesis of 2,3-unsubstituted benzo[b]furans has been established via the intramolecular cyclization of 2-aryloxyacetaldehyde acetals. By utilizing tin-exchanged H-β zeolite (Sn-β) as catalyst, a wide range of functionalized 2,3-unsubstituted benzo[b]furans could be prepared in good to excellent yields. The Sn-β zeolite catalyst also exhibited excellent shape selectivity on the cyclization of meta-substituted 2-aryloxyacetaldehyde acetals, and 6-substituted isomers were preferably formed up to 97% regio-selectivity. Moreover, Sn-β zeolite could be easily recovered and reused without any noticeable activity loss.
- Sun, Nan,Huang, Peng,Wang, Yifan,Mo, Weimin,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan
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p. 4835 - 4841
(2015/07/27)
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- Rhodium(II)-catalyzed cyclization of bis(N-tosylhydrazone)s: An efficient approach towards polycyclic aromatic compounds
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Ahead of the PAC: Polycyclic aromatic compounds (PACs) can be easily accessed by the combination of Suzuki-Miyaura cross-coupling and a [Rh 2(OAc)4]-catalyzed carbene reaction using easily available bis(N-tosylhydrazone)s as intermediates (see scheme; Ts=4-toluenesulfonyl). Copyright
- Xia, Ying,Liu, Zhenxing,Xiao, Qing,Qu, Peiyuan,Ge, Rui,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 5714 - 5717
(2012/07/28)
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- An isomerization-ring-closing metathesis strategy for the synthesis of substituted benzofurans
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Twelve substituted benzofurans were synthesized from their corresponding substituted 1-allyl-2-allyloxybenzenes using ruthenium-mediated C- and O-allyl isomerization followed by ring-closing metathesis.
- Van Otterlo, Willem A.L.,Morgans, Garreth L.,Madeley, Lee G.,Kuzvidza, Samuel,Moleele, Simon S.,Thornton, Natalie,De Koning, Charles B.
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p. 7746 - 7755
(2007/10/03)
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- Intramolecular reactions of alkynes with furans and electron rich arenes catalyzed by PtCl2: The role of platinum carbenes as intermediates
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5-(2-Furyl)-1-alkynes react, with PtCl2 as catalyst, to give phenols. On the basis of DFT calculations, a cyclopropyl platinacarbene complex was found as the key intermediate in the process. The cyclopropane and dihydrofuran rings of this intermediate open to form a carbonyl compound, which reacts with the platinum carbene to form an oxepin, which is in equilibrium with an arene oxide. When the reaction is carried out in the presence of water, dicarbonyl compounds are obtained, which support the proposed mechanism. Other cyclizations of alkynes with furans or electron-rich arenes give products of apparent Friedel-Crafts-type reactions, although these processes could also proceed by pathways involving the formation of cyclopropyl platinum carbenes.
- Martin-Matute, Belen,Nevado, Cristina,Cardenas, Diego J.,Echavarren, Antonio M.
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p. 5757 - 5766
(2007/10/03)
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- Flash vacuum pyrolysis of 3-aroylcinnolines: Interesting routes toward polynuclear aromatic compounds
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Flash vacuum pyrolysis of 3-aroylcinnolines 3 at 900°C and 0.02 Torr yielded phenanthrene and arylacetylene derivatives as the major products beside anthracene and diarylacetylene derivatives as minor products. Also, FVP of 3-(2-thienoyl)-cinnoline gave three isomeric naphthothiophenes, phenyl-2-thienylacetylene and phenylacetylene. On the other hand, 3-(2-furoyl)-cinoline gave dibenzofuran as a major product besides naphtho[1,2-b]furan and phenylacetylene.
- Ibrahim, Yehia A,Al-Awadi, Nouria A,Kaul, Kamini
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p. 7377 - 7381
(2007/10/03)
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- Synthesis and photochemistry of styryl substituted annelated furan derivatives
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New β-substituted benzo- and naphthofuryl derivatives (5, 6 and 7) of o-divinylbenzene, were synthesized and irradiated in order to form annelated bicyclo[3.2.1]octadienes. While 2-[2-(2-vinylphenyl)ethenyl]benzo[b]furan (5) upon irradiation gives the bicyclo[3.2.1]octadiene derivative (12) in 65% yield, 2-[2-(2-vinylphenyl)ethenyl]naphtho[2,1-b]furan (6) and 2-[2-(2- vinylphenyl)ethenyl]naphtho[1,2-b]furan (7), undergo cis-trans-isomerization but not form intramolecular photocycloaddition products. The mechanism of the intramolecular [2+2] photocycloaddition is explained via intermediate (17) which was proved by the formation of products (18) and (19), by irradiation in methanol and deuteromethanol.
- Sindler-Kulyk, Marija,Skoric, Irena,Tomsic, Slavica,Marinic, Zeljko,Mrvos-Sermek, Draginja
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p. 1355 - 1369
(2007/10/03)
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- (Dipropylamino)-tetrahydronaphthofurans: Centrally acting serotonin agonists and dopamine agonists-antagonists
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CNS-active aminotetralins containing phenolic moieties were transformed in a simple two-step procedure to the corresponding benzofurans. The compounds were tested in in vitro binding studies at serotonin 5-HT(1A) and 5-HT2 and dopamine D2, D3 and D4 receptors. These studies revealed that the furan homologs showed overall lower affinities than the phenol counterparts. This was also reflected that the furan homologs showed overall lower affinities than the phenol counterparts. This was reflected in vivo in biochemical studies. The benzofuran compounds retained most of the agonist/antagonist activities but with lower potency.
- Stjernloef, Peter,Lin, Chiu-Hong,Sonesson, Clas,Svensson, Kjell,Smith, Martin W.
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p. 2759 - 2764
(2007/10/03)
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- Acid-catalyzed rearrangement of cyclobutanones. V. Preparation of polycyclic aromatic dihydrofurans and dihydropyrans
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Cyclobutanones derived from α-phenyl, α,α-diphenyl, and bisphenyleneketene cycloaddition to dihydrofuran and dihydropyran were rearranged under acidic conditions to polycyclic aromatic dihydrofurans and dihydropyrans ,respectively.A mechanism for these rearrangements is proposed.
- Duperrouzel, Paul,Lee-Ruff, Edward
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