1746-11-8Relevant articles and documents
Enhanced reactivity in OH/NH/π polyfunctional systems through coupled proton/electron transfer in the excited state: The photocyclisation of 2-allyl-3-aminophenol
Leo, Edgar A.,Tormos, Rosa,Miranda, Miguel A.
, p. 1203 - 1205 (2005)
The photocyclisation rate of 2-allyl-3-(or 5-)aminophenols (1, 4 and 8) is dramatically enhanced, when compared with reference compounds, as a consequence of a coupled proton/electron transfer process. The Royal Society of Chemistry 2005.
Intramolecular hydroalkoxylation of non-activated C=C bonds catalysed by zeolites: An experimental and theoretical study
Perez-Mayoral, Elena,Matos, Ines,Nachtigall, Petr,Polozij, Miroslav,Fonseca, Isabel,Vitvarova-Prochazkova, Dana,Cejka, Jiri
, p. 1021 - 1030 (2013)
The high activity and selectivity of zeolites in the cyclisation of unsaturated alcohols is reported for the first time; the details of a reaction mechanism based on quantum chemical calculations are also provided. The high efficiency of zeolites MFI, BEA and FAU in the cyclisation of unsaturated alcohols (cis-decen-1-ol, 6-methylhept-5-en-2-ol and 2-allylphenol) to afford oxygen-containing heterocyclic rings is demonstrated. The best catalytic performance is found for zeolites with the optimum concentration of Bronsted acid sites (ca. 0.2 mmol g-1) and the minimum number of Lewis acid sites. It is proposed that the efficiency of the catalysts is reduced by the existence of the so-called dual site, at which a molecule of unsaturated alcohol can simultaneously interact with two acid sites (an OH group with one and the double bond with the other Bronsted site), which increases the interaction strength. The formation of such adsorption complexes leads to a decrease in the catalyst activity because of (i) an increase in the reaction barrier, (ii) an unfavourable conformation and (iii) diffusion limitations. A new procedure for the preparation of tetrahydrofurans and pyrans over zeolite catalysts provides important oxygen-containing heterocycles with numerous applications. The zeolite fantastic: The high efficiency of zeolites MFI, BEA and FAU in the cyclisation of unsaturated alcohols to afford oxygen-containing heterocyclic rings is demonstrated. It is proposed that the efficiency of the catalysts depends on the existence of the so-called dual site, at which a molecule of an unsaturated alcohol can simultaneously interact with two acid sites. Copyright
Transition metal-catalyzed cyclization of 2-allylphenol to 2,3-dihydro-2-methylbenzofuran without β-elimination
Hori, Kazushige,Kitagawa, Hideki,Miyoshi, Akio,Ohta, Tetsuo,Furukawa, Isao
, p. 1083 - 1084 (1998)
The intramolecular nucleophilic addition of 2-allylphenol was catalyzed by RuCl3·nH2O/AgOTf-PPh3-Cu(OTf) 2 to afford 2,3-dihydro-2-methylbenzofuran in good yield, while 2-(3-butenyl)-phenol was converted to 3,4-dihydro-2(2H)-methylbenzopyran.
Intramolecular cyclization of phenol derivatives with C{double bond, long}C double bond in a side chain
Ito, Yoshihiko,Kato, Risa,Hamashima, Kentaro,Kataoka, Yohei,Oe, Yohei,Ohta, Tetsuo,Furukawa, Isao
, p. 691 - 697 (2007)
Intramolecular cyclization of phenol derivatives with C{double bond, long}C double bond on a side chain was examined using copper and silver catalyst. For example, 2-allylphenol (1a) was converted to 2,3-dihydro-2-methylbenzofuran (2a) in 70% yield using Cu(OTf)2 or in 90% yield using AgClO4. This catalysis was applied to cyclization of 2-allylphenol derivatives, 2-(3-butenyl)phenol, benzoic acids with C{double bond, long}C double bond, 2-allyl-N-tosylaniline, and 2-(3-butenyloxy)phenol. Furthermore, allyl phenyl ether was converted to 2a via Claisen rearrangement and cyclization.
Iridium(III)-catalyzed tandem Claisen rearrangement-intramolecular hydroaryloxylation of aryl allyl ethers to form dihydrobenzofurans
Grant, Virginia H.,Liu, Bing
, p. 1237 - 1239 (2005)
Iridium(III)-catalyzed tandem Claisen rearrangement and intramolecular hydroaryloxylation of ally aryl ethers is described, which provides a mild method to prepare dihydrobenzofurans.
Aluminium(III) trifluoromethanesulfonate as an efficient catalyst for the intramolecular hydroalkoxylation of unactivated olefins: Experimental and theoretical approaches
Coulombel, Lydie,Rajzmann, Michel,Pons, Jean-Marc,Olivero, Sandra,Dunach, Elisabet
, p. 6356 - 6365 (2006)
The Al(OTf)3-catalyzed cycloisomerization of unactivated unsaturated alcohols was studied from experimental and theoretical points of view. A series of cyclic ethers was obtained in excellent yields and regioselectivities. This catalyst system provides one of the most straightforward routes to cyclic ethers with Markovnikov-type regioselectivity under mild conditions. Theoretical and NMR studies were carried out in order to better determine the mechanism of this reaction. The NMR studies were in agreement with preferential complexation of Al(OTf)3 to the oxygen atom of the unsaturated alcohol, but did not exclude complexation to the double bond of the alcohol. Theoretical calculations indicated strong acidification of the hydroxyl proton when Al(OTf)3 was complexed to the alcohol oxygen atom. A plausible catalytic cycle for the Al(OTf)3-catalyzed intramolecular hydroalkoxylation of unactivated olefins is proposed.
Intramolecular Cyclization using Methyl(bismethylthio)sulphonium Salts. Part 1. 2,3-Dihydrobenzofurans
Capozzi, Giuseppe,Lucchini, Vittorio,Marcuzzi, Franco,Modena, Giorgio
, p. 3106 - 3110 (1981)
Methyl(bismethylthio)sulphonium hexachloroantimonate (1a) reacts under mild conditions with 2-allylphenol (3a) to give 2-(methylthiomethyl)-2,3-dihydrobenzofuran (4a).Methylthiolation at position 5 in the heterocycle may also occur.With 4-substituted 2-allylphenols (3b-d) (substituents: methyl, chloro, nitro) only the corresponding 5-substituted 2-(methylthiomethyl)-2,3-dihydrobenzofurans (4b-d) are obtained.
Solid-phase synthesis of 2-iodomethyl-2, 3-dihydrobenzofurans using recyclable polymer-supported selenium bromide
Sheng, Shouri,Hu, Minggang,Wu, Dan,Cai, Mingzhong,Huang, Xian
, p. 345 - 348 (2009)
Reaction of polymer-supported selenium bromide with ortho allylated phenols and subsequent cleavage from the polymer by treatment of methyl iodide efficiently afforded 2-iodomethyl-2, 3-dihydrobenzofurans in good yields and high purities. The polymeric re
STRONGLY LEWIS ACIDIC METAL-ORGANIC FRAMEWORKS FOR CONTINUOUS FLOW CATALYSIS
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Paragraph 0230-0233; 0239; 0255, (2021/02/26)
Lewis acidic metal-organic framework (MOF) materials comprising triflate-coordinated metal nodes are described. The materials can be used as heterogenous catalysts in a wide range of organic group transformations, including Diels-Alder reactions, epoxide-ring opening reactions, Friedel-Crafts acylation reactions and alkene hydroalkoxylation reactions. The MOFs can also be prepared with metallated organic bridging ligands to provide heterogenous catalysts for tandem reactions and/or prepared as composites with support particles for use in columns of continuous flow reactor systems. Methods of preparing and using the MOF materials and their composites are also described.
Enantio- and Diastereoselective, Complete Hydrogenation of Benzofurans by Cascade Catalysis
Gallagher, Timothy,Glorius, Frank,Hu, Tianjiao,Moock, Daniel,Wagener, Tobias
supporting information, p. 13677 - 13681 (2021/05/10)
We report an enantio- and diastereoselective, complete hydrogenation of multiply substituted benzofurans in a one-pot cascade catalysis. The developed protocol facilitates the controlled installation of up to six new defined stereocenters and produces architecturally complex octahydrobenzofurans, prevalent in many bioactive molecules. A unique match of a chiral homogeneous ruthenium-N-heterocyclic carbene complex and an in situ activated rhodium catalyst from a complex precursor act in sequence to enable the presented process.
