- Acid-promoted selective synthesis of trifluoromethylselenolated benzofurans with Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate
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A Br?nsted acid-promoted trifluoromethylselenolation of benzofurans was disclosed by using Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate as a stable and easily prepared electrophilic trifluoromethylselenolating reagent. A wide range of SeCF3-substituted benzofuran derivatives were obtained in moderate to good yields with excellent regioselectivity. The tandem cyclization/trifluoromethylselenolation procedure of 1-methoxy-2-(arylethynyl)benzenes were also realized by engaging FeCl3 as the catalyst.
- Liu, Juyan,Tian, Miaomiao,Li, Ankun,Ji, Liangshuo,Qiu, Di,Zhao, Xia
-
supporting information
(2021/02/01)
-
- PALLADIUM ACYCLIC DIAMINOCARBENE COMPLEXES AS PRECATALYSTS FOR HIYAMA COUPLING AND THE TANDEM ONE-POT FLUORIDE FREE HIYAMA COUPLING/CYCLIZATION FOR THE SYNTHESIS OF BIOLOGICALLY RELEVANT
-
The present invention provides Acyclic diaminocarbene complex of formula (I): Wherein, M is palladium; X is monoanionic ligand selected from Cl, Br or I; Where R1 is different from R2; R1 is selected from the group consisting of alkyl or aryl, each of which have 4 to 20 carbon atoms, and may optionally contain one or more heteroatoms; R2 is selected from the group consisting of alkyl, or aryl each of which have 4 to 20 carbon atoms, and may optionally contain one or more heteroatoms. The said palladium diamino carbine complex of the present invention are particularly useful as catalyst from Hiyama cross-coupling reaction.
- -
-
Paragraph 0108; 0109; 0114-0115
(2020/05/06)
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- Palladium complexes with an annellated mesoionic carbene (MIC) ligand: Catalytic sequential Sonogashira coupling/cyclization reaction for one-pot synthesis of benzofuran, indole, isocoumarin and isoquinolone derivatives
-
Two Pd(ii) complexes (1 and 2) featuring a fused π-conjugated imidazo[1,2-a][1,8]naphthyridine-based mesoionic carbene ligand have been synthesized and structurally characterized. Both complexes effectively catalyze the one-pot synthesis of benzofuran starting from phenylacetylene and 2-iodophenol under mild conditions. Complex 1 is found to be an excellent catalyst for the straightforward access to a library of benzofuran, indole, isocoumarin and isoquinolone derivatives by the reaction of terminal alkynes with 2-iodo derivates of phenol, N-methyl aniline, benzoic acid and N-methyl benzamide, respectively. The general utility of the catalytic method is demonstrated using a variety of diversely substituted terminal alkynes and the corresponding desired products are obtained in good to excellent yields. On the basis of control experiments, a two-cycle mechanism is proposed which involves the Sonogashira coupling of 2-iodo derivatives with alkynes and the subsequent cyclization of the corresponding 2-alkynyl compounds.
- Bera, Jitendra K.,Daw, Prosenjit,Reshi, Noor U Din,Tyagi, Akshi
-
supporting information
p. 15238 - 15248
(2020/11/18)
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- A 2 - substituted benzofuran compound of the catalytic synthesis method
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The invention discloses a 2 - substituted benzofuran compound of the catalytic synthesis method, comprises the following steps: normal temperature and pressure, the 2 - alkynyl substituted phenol dissolved in acetonitrile, wherein the 2 - alkynyl substituted phenol with acetonitrile molar volume ratio of 1: 1mmol/mL, to obtain 2 - alkynyl substituted phenol acetonitrile solution; and then to the acetonitrile solution in adding cuprous chloride and cesium carbonate, wherein the cuprous chloride and cesium carbonate of respectively the molar consumption of 2 - alkynyl-substituted phenol mole amount of 5%; after, room temperature stirring 6 hours, produced by the reaction of 2 - substituted benzofuran compound. The invention 2 - substituted benzofuran compound of the catalytic method for synthesis of low cost, high yield, its preparation 1 g of 2 - substituted benzofuran compounds required the cost of the catalyst the prior by iridium catalyst is a catalyst of the synthetic method has lowered 2 orders of magnitude, to improve the yield of the 88.5 - 95.8%.
- -
-
Paragraph 0016; 0017; 0018
(2019/05/22)
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- Heterogeneous Nickel-Catalyzed Cross-Coupling between Aryl Chlorides and Alkyllithiums Using a Polystyrene-Cross-Linking Bisphosphine Ligand
-
A polystyrene-cross-linking bisphosphine ligand PS-DPPBz was used for Ni-catalyzed cross-coupling with organolithiums. A bench-stable precatalyst [NiCl2(PS-DPPBz)] enabled efficient coupling reactions between aryl chlorides and alkyllithiums. The heterogeneous Ni system showed good reusability. (Figure presented.).
- Yamazaki, Yuki,Arima, Nozomi,Iwai, Tomohiro,Sawamura, Masaya
-
supporting information
p. 2250 - 2254
(2019/03/21)
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- Preparation method of amiodarone hydrochloride
-
The invention relates to a preparation method of amiodarone hydrochloride. According to the preparation method, synthesis of intermediate 2-butylbenzofuran is realized under effect of a catalyst, a cocatalyst, and an acid binding agent, through Sonogashira coupling cyclization reaction of 2-iodo phenol and 1-acetylene in an organic solvent at a 2-iodo phenol to 1-acetylene molar ratio of 1:09-1.3,wherein reaction temperature ranges from 30 to 60 DEG C, and reaction time ranges from 12 to 38h. Compared with the prior art, the advantages are that: operation is simplified; operation convenienceand product stability are improved; controlling of the ratio of the catalyst to the materials is capable of increasing the purities and yields of intermediates; no column chromatography purifying is needed; cost is reduced; production efficiency is increased at the same time; and convenience is provided for industrial large scale production.
- -
-
Paragraph 0013; 0019-0026
(2019/08/12)
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- CuI catalyzed domino coupling–cyclization of 2-iodo-phenols and 1-alkynes to the synthesis of 2-substituted benzo[b]furans/furo-pyridines
-
CuI/proline-catalyzed coupling reaction of 2-iodo-phenols with terminal alkynes and the following cyclization process is carried out successively in DMSO at 80 °C. Under this tandem process, 2-substituted benzo[b]furans/furo-pyridines were synthesized in good to excellent yields with a great diversity.
- Chen, Ze-Pin,Zhou, Yi,Shui, Meng-Zhu,Liu, Feng
-
supporting information
p. 133 - 136
(2018/12/11)
-
- Preparation method of amiodarone hydrochloride intermittent
-
The invention belongs to the field of medicine synthesis, and relates to a preparation method of an amiodarone hydrochloride intermittent. The method is characterized by including the following stepsthat 1, under an alkaline condition, in the presence of a phase transfer catalyst, a compound 1 and a compound 2 are subjected to nucleophilic substitution reaction to obtain a compound 3; 2, under analkaline condition, the compound 3 is hydrolyzed to generate a compound 4; 3, the compound 4 is subjected to intramolecular aldol condensation, decarboxylation and dehydration to obtain a compound 5;4, a compound 6 and thionyl chloride are subjected to heating reaction to obtain a compound 7; 5, under the presence of lewis acid, the compound 5 and the compound 7 are subjected to friede-crafts acylation reaction to obtain a compound 8; 6, under the presence of lewis acid, the compound 8 is subjected to demethylation to generate a compound 9, namely the amiodarone hydrochloride intermittent 2-butyl-3-(4-hydroxybenzoyl)benzofuran. The preparation method of the amiodarone hydrochloride intermittent has the advantages of being short in reaction time, high in product purity and high in yield,and the amiodarone hydrochloride intermittent is suitable for large-scale industrial production.
- -
-
Paragraph 0019; 0055; 0058; 0064; 0067; 0072; 0075
(2019/01/13)
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- Indium(III)-Catalyzed Synthesis of Benzo[ b]furans by Intramolecular Hydroalkoxylation of ortho-Alkynylphenols: Scope and Mechanistic Insights
-
Indium(III) halides catalyze the hydroalkoxylation reaction of ortho-alkynylphenols to afford benzo[b]furans in good yields. The reaction proceeds with 5-endo-dig regioselectivity with a variety of phenols functionalized at the arene and alkyne moieties in high yields using InI3 (5 mol %) in DCE. Experimental and computational studies support a mechanism based on the indium(III) π-Lewis acid activation of the alkyne followed by nucleophilic addition of the phenol and final protodemetalation to afford the corresponding benzo[b]furan. DFT calculations suggest that dimer In2I6 is the catalytic species through a novel double coordination with the alkyne and the hydroxyl group.
- Alonso-Mara?ón, Lorena,Martínez, M. Montserrat,Sarandeses, Luis A.,Gómez-Bengoa, Enrique,Pérez Sestelo, José
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p. 7970 - 7980
(2018/06/22)
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- Preparation method of amiodarone hydrochloride intermediate 2-butylbenzofuran
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The invention relates to a preparation method of an amiodarone hydrochloride intermediate 2-butylbenzofuran. The preparation method comprises the following steps: A, with methyl 2-(2-aldehydephenoxy)hexanoate as a reaction substrate, under the action of potassium carbonate and potassium iodide, reacting in an organic solvent until a raw material disappears; B, adding water and an organic solvent into a reaction solution obtained in the step A, thoroughly stirring for extracting, separating out an organic phase, drying and then concentrating under reduced pressure to obtain yellow transparent liquid 2-butylbenzofuran. The 2-butylbenzofuran prepared by the preparation method is high in purity; the operation is simple; use of cumbersome column chromatography is avoided; the preparation methodis suitable for large-scale industrial production.
- -
-
Paragraph 0050; 0051; 0057
(2018/11/03)
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- Visible-Light-Driven alkyne hydro-/carbocarboxylation using CO2 via iridium/cobalt dual catalysis for divergent heterocycle synthesis
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We present herein the first visible-light-driven hydrocarboxylation as well as carbocarboxylation of alkynes using CO2 via an iridium/cobalt dual catalysis. Such transformations provide access to various pharmaceutically important heterocycles in a one-pot procedure from readily available alkynes. Coumarins, 2-quinolones, and 2-benzoxepinones were directly accessed through a one-pot alkyne hydrocarboxylation/alkene isomerization/cyclization sequence in which the Ir photocatalyst serves a dual role to promote single-electron transfer in alkyne hydrocarboxylation and energy transfer in the subsequent alkene isomerization. Moreover, an unprecedented cobalt carboxylation/acyl migration cascade enables alkyne difunctionalization to introduce γ-hydroxybutenolides with high efficiency. We expect that this cascade strategy will inspire new perspectives for alkyne and alkene difunctionalization.
- Hou, Jing,Ee, Aloysius,Feng, Wei,Xu, Jin-Hui,Zhao, Yu,Wu, Jie
-
supporting information
p. 5257 - 5263
(2018/04/24)
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- Amiodarone hydrochloride preparation method
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The invention belongs to the field of medicine, and especially relates to an amiodarone hydrochloride preparation method. The method takes 2-hydroxybenzaldehyde and 2-alkyl halohexoic acid ester as the raw materials to prepare 2-butylbenzofuran, 2-butylbenzofuran is taken as the raw material, and is subjected to the steps of friedel-crafts acylation, demethylation, iodination, etherification and salt forming to obtain the amiodarone hydrochloride. By employing the method, the raw materials have the advantages of low cost and easy acquisition, the process is simple, and 2-butylbenzofuran and amiodarone hydrochloride with high purity and high yield can be obtained, the cost is low, the waste water is little, and the method is suitable for industrial production.
- -
-
Paragraph 0089-0091
(2018/03/13)
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- Synthesis of substituted benzofurans and indoles by Zn-catalyzed tandem Sonogashira-cyclization strategy
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Transition metal catalyzed cross-coupling reactions are one of the predominant strategies for the construction of heterocyclic structures which possess wide applications in the synthesis of natural products, pharmaceuticals, polymers, etc. Due to the vast importance of substituted benzofurans and indoles, numerous synthetic methodologies have been introduced for their synthesis. Among these methods, transition metal catalyzed cyclization reactions possess a unique position. In this manuscript, we disclose the first and efficient zinc-catalyzed protocol for the cyclization reactions of alkynes with 2-iodophenol and 2-iodoaniline leading to benzofurans and indoles respectively via a tandem Sonogashira coupling-cyclization process. Among the different metal catalysts, zinc has enormous potential due to its great availability, non-toxicity, eco-friendly and inexpensive nature. Zn(II) with N,N′-dimethylethylenediamine represents a suitable and efficient catalytic system for the desired tandem CC coupling-cyclization reactions, and a broad spectrum of functional groups are tolerated during the catalysis. A variety of substituted benzofurans and indoles have been successfully prepared in moderate to good yields under this new protocol.
- Thankachan, Amrutha P.,Sindhu, Kallikkakam S.,Ujwaldev, Sankuviruthiyil M.,Anilkumar, Gopinathan
-
supporting information
p. 536 - 540
(2017/01/16)
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- Gold-Catalyzed Domino Synthesis of Functionalized Benzofurans and Tetracyclic Isochromans via Formal Carboalkoxylation
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A domino synthesis of benzofurans with the modification of side chains from α-alkoxyalkyl o-alkynylaryl ethers (n = 0) and electron-rich arenes has been developed. In the present domino reaction, which would proceed via the α-alkoxyalkylation of arenes with an intermediate in the migratory cycloisomerization of o-alkynylaryl ethers followed by the nucleophilic addition of benzofurans to benzyl ethers, a cationic Au(III) catalyst activates the C-C π bond and the C-O σ bond. The present method could be extended to Au(I)-catalyzed domino synthesis of tetracyclic isochromans from α-alkoxyalkyl (o-alkynylaryl)methyl ethers (n = 1) and aryl methoxymethyl ethers.
- Obata, Tomoyuki,Suzuki, Sho,Nakagawa, Asuka,Kajihara, Ryota,Noguchi, Keiichi,Saito, Akio
-
supporting information
p. 4136 - 4139
(2016/08/30)
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- Pd-Catalyzed Isocyanide Assisted Reductive Cyclization of 1-(2-Hydroxyphenyl)-propargyl Alcohols for 2-Alkyl/Benzyl Benzofurans and Their Useful Oxidative Derivatization
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An unusual Pd-catalyzed isocyanide assisted 5-exo-dig reductive cyclization of 1-(2-hydroxyphenyl)-propargyl alcohols is achieved for 2-alkyl/benzyl benzofurans. The reaction features a high substrate scope, insensitivity to air, and excellent product yielding. Further, a direct metal-free C-H functionalization (azidation, alkoxylation, and hydroxylation) and selective oxidative cleavage of thus synthesized 2-benzylfurans are described for azido-, alkoxy-, hydroxyl-, amide-, and tetrazolyl adducts.
- Rajesh, Manda,Thirupathi, Nuligonda,Jagadeshwar Reddy, Thota,Kanojiya, Sanjeev,Sridhar Reddy, Maddi
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p. 12311 - 12320
(2016/01/09)
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- Cobalt-Catalyzed Negishi Cross-Coupling Reactions of (Hetero)Arylzinc Reagents with Primary and Secondary Alkyl Bromides and Iodides
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We report a cobalt-catalyzed cross-coupling of di(hetero)arylzinc reagents with primary and secondary alkyl iodides or bromides using THF-soluble CoCl2·2 LiCl and TMEDA as a ligand, which leads to the corresponding alkylated products in up to 88% yield. A range of functional groups (e.g. COOR, CN, CF3, F) are tolerated in these substitution reactions. Remarkably, we do not observe rearrangement of secondary alkyl iodides to unbranched products. Additionally, the use of cyclic TBS-protected iodohydrins leads to trans-2-arylcyclohexanol derivatives in excellent diastereoselectivities (up to d.r.=99:1).
- Hammann, Jeffrey M.,Haas, Diana,Knochel, Paul
-
supporting information
p. 4478 - 4481
(2015/04/14)
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- Asymmetric hydrogenation of furans and benzofurans with iridium-pyridine-phosphinite catalysts
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Enantioselective hydrogenation of furans and benzofurans remains a challenging task. We report the hydrogenation of 2- and 3-substituted furans by using iridium catalysts that bear bicyclic pyridine-phosphinite ligands. Excellent enantioselectivities and high conversions were obtained for monosubstituted furans with a 3-alkyl or 3-aryl group. Furans substituted at the 2-position and 2,4-disubstituted furans proved to be more difficult substrates. The best results (80-97% conversion, 65-82% enantiomeric excess) were obtained with monosubstituted 2-alkylfurans and 2-[4-(trifluoromethyl)phenyl]furan. Benzofurans with an alkyl substituent at the 2- or 3-position also gave high conversions and enantioselectivity, whereas 2-aryl derivatives showed essentially no reactivity. The asymmetric hydrogenation of a 3-methylbenzofuran derivative was used as a key step in the formal total synthesis of the cytotoxic naphthoquinone natural product (-)-thespesone.
- Pauli, Larissa,Tannert, Re,Scheil, Robin,Pfaltz, Andreas
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supporting information
p. 1482 - 1487
(2015/01/30)
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- Palladium nanoparticles catalyzed synthesis of benzofurans by a domino approach
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Abstract Palladium nanoparticles (PdNPs) were used as a catalyst for the one-pot synthesis of a variety of benzofurans by Sonogashira cross-coupling reactions under ambient conditions. The catalyst could be recycled without significant loss in its activity.
- Mandali, Pavan Kumar,Chand, Dillip Kumar
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p. 1661 - 1668
(2015/06/02)
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- Highly efficient heterogeneous synthesis of benzofurans under aqueous condition
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Highly efficient organic reactions in water are important for designing environmental-friendly and low cost synthetic processes. Herein, we demonstrate an intermediate-in-water strategy for the heterogeneous synthesis of benzofurans in aqueous media. The cyclization reaction of 2-(phenylethynyl)phenol to 2-phenylbenzofuran cannot proceed in pure water. However, this reaction can be efficiently promoted by the formation of sparingly soluble intermediate in the presence of alkaline. Quantitative conversion of a variety of substrates to benzofuran derivatives has been achieved in the absence of noble metal catalyst. Other remarkable features including easy-isolation and purification of product, along with wide range of functional group tolerance render the methodology promising in the realm of green-synthesis.
- Sun, Shi-Xin,Wang, Jun-Jie,Xu, Zi-Jun,Cao, Lu-Ya,Shi, Zi-Fa,Zhang, Hao-Li
-
supporting information
p. 3798 - 3806
(2014/05/20)
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- Nickel-NHC-catalyzed cross-coupling of 2-methylsulfanylbenzofurans with alkyl grignard reagents
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NiCl2(PPh3)(IPr) catalyzes cross-coupling reactions of 2-methylsulfanylbenzofurans with alkyl Grignard reagents. Other nickel complexes such as NiCl2(dppe) failed to catalyze the same reaction. The alkylation is applicable to the synthesis of a couple of protein tyrosine phosphatase inhibitors, 3-(4-biphenylyl)-2-alkylbenzofurans.
- Baralle, Alexandre,Otsuka, Shinya,Guérin, Vincent,Murakami, Kei,Yorimitsu, Hideki,Osuka, Atsuhiro
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supporting information
(2015/02/19)
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- Chemoselectivity control: Gold(I)-catalyzed synthesis of 6,7-dihydrobenzofuran-4(5H)-ones and benzofurans from 1-(alkynyl)-7- oxabicyclo[4.1.0]heptan-2-ones
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New and chemoselective gold(I)-catalyzed transformations of 1-(arylethynyl)-7-oxabicyclo[4.1.0]- heptan-2-ones were developed. Two completely different products - 6,7-dihydrobenzofuran-4(5H)-ones and benzofurans - could be obtained from the same starting material. The selectivity is determined by the ligand of the gold catalyst: triphenylphosphine delivers 6,7-dihydrobenzofuran-4(5H)-ones, and 1,3-bis(diisopropylphenyl)imidazol-2- ylidene leads to benzofurans. Eleven examples of each case are provided. The mechanistic suggestions for the pathways to both product types are supported by isotope labeling experiments. Complete chemoselectivity control of gold(I)-catalyzed transformations of 1-(arylethynyl)-7-oxabicyclo[4.1.0]heptan- 2-ones, which can be achieved by changing the ligand of the gold catalyst, allows two different products to be obtained from the same starting material, namely, 6,7-dihydrobenzofuran-4(5H)-ones and benzofurans (see scheme), both of which are potent building blocks for synthetic chemistry. IPr: 1,3-bis(diisopropylphenyl)imidazol-2-ylidene. Copyright
- Wang, Tao,Shi, Shuai,Vilhelmsen, Mie Hojer,Zhang, Tuo,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 12512 - 12516
(2013/09/23)
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- Practical synthesis of indoles and benzofurans in water using a heterogeneous bimetallic catalyst
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This paper describes the preparation of indoles, azaindoles and benzofurans in pure water by using a new heterogeneous Pd-Cu/C catalyst through a cascade Sonogashira alkynylation-cyclization sequence. Details of the optimization studies and the substrate scope are discussed. This procedure allows the preparation of heterocycles with good yields and is tolerant to a wide variety of functional groups.
- Rossy, Cybille,Fouquet, Eric,Felpin, Francois-Xavier
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supporting information
p. 1426 - 1431
(2013/08/23)
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- Synthesis of 2-substituted benzofurans from o-iodophenols and terminal alkynes with a recyclable palladium catalyst supported on nano-sized carbon balls under copper- and ligand-free conditions
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We have developed a one-step synthesis of benzofurans from o-iodophenol and various terminal alkynes, by using Pd catalyst supported on nano-sized carbon balls (NCB) under copper- and ligand free conditions. This recyclable catalyst could be reused more than 5 times in the same heteroannulation reaction. The results have demonstrated that diverse 2-substituted benzofurans with tolerant functional groups can be prepared simply and conveniently under these conditions.
- Yum, Eul Kgun,Yang, Ok-Kyung,Kim, Ji-Eun,Park, Hee Jung
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p. 2645 - 2649
(2013/10/22)
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- A photochemical route to 2-substituted benzo[b]furans
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2-Substituted benzo[b]furans were synthesized by a one-step metal-free photochemical reaction between 2-chlorophenol derivatives and terminal alkynes by tandem formation of an aryl-C and a C-O bond via an aryl cation intermediate. The mild conditions and the application to chlorophenols rather of the more expensive bromo or iodo analogues makes this procedure environmentally convenient.
- Protti, Stefano,Fagnoni, Maurizio,Albini, Angelo
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experimental part
p. 6473 - 6479
(2012/10/08)
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- Dehydrative C-H alkylation and alkenylation of phenols with alcohols: Expedient synthesis for substituted phenols and benzofurans
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A well-defined cationic Ru-H complex catalyzes the dehydrative C-H alkylation reaction of phenols with alcohols to form ortho-substituted phenol products. Benzofuran derivatives are efficiently synthesized from the dehydrative C-H alkenylation and annulation reaction of phenols with 1,2-diols. The catalytic C-H coupling method employs cheaply available phenols and alcohols, exhibits a broad substrate scope, tolerates carbonyl and amine functional groups, and liberates water as the only byproduct.
- Lee, Dong-Hwan,Kwon, Ki-Hyeok,Yi, Chae S.
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supporting information; experimental part
p. 7325 - 7328
(2012/06/16)
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- Ruthenium NHC catalyzed highly asymmetric hydrogenation of benzofurans
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H2-O-T! Aromatic O-heterocycles are a challenging substrates for asymmetric hydrogenation (H2). An in situ formed chiral N-heterocyclic carbene (NHC) ruthenium complex allows the high yielding, completely regioselective, and highly asymmetric hydrogenation of substituted benzofurans at room Temperature, giving valuable 2,3-dihydrobenzofurans (see scheme). Copyright
- Ortega, Nuria,Urban, Slawomir,Beiring, Bernhard,Glorius, Frank
-
supporting information; experimental part
p. 1710 - 1713
(2012/04/05)
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- Domino sonogashira coupling/cyclization reaction catalyzed by copper and ppb levels of palladium: A concise route to indoles and benzo[b]furans
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Both indoles and benzo[b]furans can be obtained in high yield by the reactions of 2-iodoaniline derivatives and 2-iodophenols with terminal alkynes under mild conditions, namely in the presence of cuprous iodide (10-mol%) and a base in ethanol or 1,4-dioxane. Further investigation reveals that palladium contaminants as low as 100 ppb are responsible for these successful couplings. It is worth noting that simple aliphatic substituted terminal alkynes could be tolerated to smoothly produce indole and benzo[b]furan derivatives. Copyright
- Wang, Ruiping,Mo, Song,Lu, Yongzhong,Shen, Zengming
-
supporting information; experimental part
p. 713 - 718
(2011/05/15)
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- Csp3-Csp2 palladium-catalyzed cross-coupling reaction of trialkylbismuth reagents with aryl, heteroaryl, and vinyl halides and triflates
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The palladium-catalyzed cross-coupling reaction of trialkylbismuth reagents with aryl and heteroaryl halides and triflates is reported. Moderate to good yields were obtained for the transfer of primary alkyl groups. The reaction tolerates numerous functional groups on the electrophilic and nucleophilic partners. The cross-coupling of -bromostyrene with tris(1,3-dioxan-2-ylethyl) bismuth is also reported. Georg Thieme Verlag Stuttgart - New York.
- Gagnon, Alexandre,Albert, Vincent,Duplessis, Martin
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experimental part
p. 2936 - 2940
(2011/02/28)
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- Domino rhodium(I)-catalysed reactions for the efficient synthesis of substituted benzofurans and indoles
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Rhodium(I) catalysts promote the transformation of o-alkynyl phenols and anilines to the corresponding benzo[b]furans and indoles. The reaction is postulated to proceed via a transient 3-rhodium heterocycle intermediate, which can be trapped with suitable electrophiles to give poly-substituted heterocycles. In the case of mono-substituted electron-withdrawn electrophiles, excellent yield and selectivity for conjugate addition versus Heck-Mizoroki reaction can be achieved. In the case of 2-alkynyl pyridine electrophiles, novel 2-(benzofuran-3-yl)vinylpyridines are formed.
- Boyer, Alistair,Isono, Naohiro,Lackner, Sebastian,Lautens, Mark
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scheme or table
p. 6468 - 6482
(2010/10/03)
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- Controlled synthesis of 2-and 3-substituted benzo[ b ]furans
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A controlled regioselective synthesis of either C-2 or C-3 substituted benzo[b]furans from readily accessible 1-(2-hydroxyphenyl)-2-chloroethanones is described. Addition of a range of Grignard reagents to the α-chloro ketones generates alkoxide intermediates, which can form either 2-substituted benzo[b]furans via a [1,2]-aryl migration or 3-substituted benzo[b]furans via a direct cyclization and dehydration sequence. A temperature-dependent [1,2]-aryl migration mechanism for the formation of 2-substituted benzo[b]furan is proposed.
- Pei, Tao,Chen, Cheng-Yi,Dimichele, Lisa,Davies, Ian W.
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supporting information; experimental part
p. 4972 - 4975
(2010/12/25)
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- Rhodium(I)-catalyzed cyclization reaction of o-alkynyl phenols and anilines. Domino approach to 2,3-disubstituted benzofurans and indoles
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A rhodium-catalyzed cyclization of o-alkynylphenols and anilines followed by intermolecular conjugate addition that succeeds with alkyl and aryl alkynes is reported. In this reaction, 2,3-disubstituted benzofurans or indoles are obtained in one pot in good to excellent yields.
- Isono, Naohiro,Lautens, Mark
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supporting information; experimental part
p. 1329 - 1331
(2009/10/02)
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- TiCl4-catalyzed indirect anti-Markovnikov hydration of alkynes: Application to the synthesis of benzo[b]furans
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(Chemical Equation Presented) An efficient methodology for the indirect anti-Markovnikov hydration of unsymmetrically substituted terminal and internal alkynes is based on TiCl4-catalyzed hydroamination reactions. Its application to ortho-alkynylhaloarenes, followed by a copper-catalyzed O-arylation, provides flexible access to substituted benzo[b]furans.
- Ackermann, Lutz,Kaspar, Ludwig T.
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p. 6149 - 6153
(2008/02/09)
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- 3-Zinciobenzofuran and 3-zincioindole: Versatile tools for the construction of conjugated structures containing multiple benzoheterole units
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(Chemical Equation Presented) Closing the ring: Thermally stable but reactive 3-zinciobenzofurans and indoles were synthesized by metalative cyclization of 2-ynyl phenols or anilines. Furthermore, a variety of extended π-conjugated molecules were obtained by Pd-catalyzed cross-coupling reactions of these heterocycles with mono- or polyhalo-substituted arenes and alkenes (R2Haln; see scheme; Bn = benzyl).
- Nakamura, Masaharu,Ilies, Laurean,Otsubo, Saika,Nakamura, Eiichi
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p. 944 - 947
(2007/10/03)
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- 2,3-Disubstituted benzofuran and indole by copper-mediated C-C bond extension reaction of 3-zinciobenzoheterole
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A metalative 5-endo-dig cyclization reaction of 2-ynylphenoles or anilines effected by BuLi and ZnCl2 produces 3-zinciobenzoheteroles in excellent yield. These intermediates have been transmetalated to the corresponding cuprates and allowed to react with electrophiles to produce a variety of 2,3-disubstituted benzofurans and indoles.
- Nakamura, Masaharu,Ilies, Laurean,Otsubo, Saika,Nakamura, Eiichi
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p. 2803 - 2805
(2007/10/03)
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- Efficient cyclization of 2-phenoxyalkanals to 2-alkylbenzo[b]furans
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A new and efficient route to 2-alkylbenzo[b]furans via acid-catalyzed cyclization of 2-phenoxyalkanals under mild conditions over amberlyst-15 resin has been described. Copyright Taylor & Francis, Inc.
- Witczak,Kwiecien
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p. 2223 - 2230
(2007/10/03)
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- A new structural alternative in benzo[b]furans for antimicrobial activity
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Two series of 2-substituted and three new diacetyl benzofurans were synthesized through palladium-catalyzed reactions and their in vitro antimicrobial spectra were assessed. The compounds demonstrated mild to significant growth inhibition against antibiotic-susceptible standard and clinically isolated strains of Gram-positive and Gram-negative bacteria as well as human fungal pathogens. Ampicillin and kanamycin were used as references for antibacterial screening; nystatin and amphotericin B were used for antifungal screening. Varying substitution at the benzofuran moiety and subsequent antimicrobial screening identified the C-3-acetyl functionality as a new structural alternative for optimal antimicrobial property in the benzofuran class of compounds.
- Khan, M. Wahab,Alam, M. Jahangir,Rashid,Chowdhury
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p. 4796 - 4805
(2007/10/03)
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- Synthesis of 2-alkylbenzofurans via acid-catalyzed cyclization of 1,1-dimethoxy-2-phenoxyalkanes
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Treatment of 2-phenoxyalkanals 1a-e with methanol at room temperature under homo-or heterogeneous acid-catalysis conditions leads to formation of diacetal as well as some quantities of appropriate 2-alkylbenzofurans. 2-Alkylbenzofurans 3a-e were obtained in high yields via cyclization of the 1,1 -dimethoxy-2-phenoxyalkanes 2a-e under mild conditions over Amberlyst 15.
- Kwiecien,Witczak,Rosiak
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p. 249 - 254
(2007/10/03)
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- Novel highly regioselective VO(acac)2/TBHP mediated oxidation of o-alkenyl phenols to o-hydroxybenzyl ketones
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A novel mild methodology for the preparation of o-hydroxybenzyl ketones is described starting from o-alkenyl phenols and based on the VO(acac)2/TBHP (2 mol %/1.2 equiv) system. VO(acac)2 first catalyzes the epoxidation of o-alkenyl phenols and then the rearrangement of the epoxyphenols to ketones via the selective benzylic C-O cleavage and 1,2 hydride migration. The protocol has also been applied to set up a useful and easy one-pot conversion of o-alkenyl phenols to benzo[b]furans by means of the sequential addition of TFA, after the generation of the intermediate o-hydroxybenzyl ketones.
- Lattanzi, Alessandra,Senatore, Antonello,Massa, Antonio,Scettri, Arrigo
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p. 3691 - 3694
(2007/10/03)
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- Synthesis of polyfunctional indoles and related heterocycles mediated by cesium and potassium bases
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A general preparation of 2-substituted indoles starting from functionalized 2-alkynylanilines has been developed. This base mediated reaction has also been used to synthesize the heterocyclic core of the marine alkaloid hinckdentine A. Furthermore the reaction was successfully adapted to the solid phase. Benzofurans and isoindolones could also be prepared with this method.
- Koradin, Christopher,Dohle, Wolfgang,Rodriguez, Alain L.,Schmid, Bertram,Knochel, Paul
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p. 1571 - 1587
(2007/10/03)
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- Aromatic C-H insertion of β-phenoxyalkylidenecarbenes generated by reaction of alkynyl(p-phenylene)bisiodonium ditrifluoro-methanesulfonates (ditriflates) with phenoxide anions
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Reaction of alkynyl(p-phenylene)bisiodonium ditriflates with sodium phenoxide in methanol provides 2-substituted benzofurans in 49-62% yields. This result indicates that β-phenoxyalkylidenecarbenes are generated by the reaction with phenoxide anion and undergo novel intramolecular aromatic C-H insertion to afford benzofurans. 2-Phenoxy-2-phenylethenylidene generated analogously in situ underwent competing processes of aromatic C-H insertion and 1,2-phenyl migration. The corresponding reactions with 4-substituted phenoxide ions also afforded 5-substituted benzofurans and, as the minor products, 2-aryloxy-1-iodoalk-1-enes which were probably derived from the intermediate vinyliodonium salts. Reactions of alkynyl(p-phenylene)bisiodonium ditriflates with sodium [2H5]phenoxide (98% 2H) in methanol gave deuterated 2-alkylbenzofurans in 35-40% yields and the hydrogen at the 3-position of the benzofurans was deuterated completely. This result strongly supports selective aromatic C-H insertion of the in situ generated β-phenoxyalkylidenecarbenes.
- Kitamura, Tsugio,Zheng, Lei,Fukuoka, Takahiro,Fujiwara, Yuzo,Taniguchi, Hiroshi,Sakurai, Makoto,Tanaka, Ryuichi
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p. 1511 - 1515
(2007/10/03)
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- Benzofuran Systems. Synthesis and Biological Examination of 1-(3-Benzofuranyl)-2-phenylethanones
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Novel 1-(3-benzofuranyl)-2-phenylethanones 4a-d have been prepared by acetylation of 2-alkylbenzofurans 2a-c with phenylacetyl chlorides 3a-b. The methoxy derivatives 4b-d have been demethylated to the corresponding phenols 5b-d with pyridinium hydrochloride. An attempt to obtain the derivatives of 4d and 5a iodinated in the phenyl ring has been undertaken. The novel compounds have been characterized by ir and nmr spectra and their biological activity examined.
- Kwiecien, Halina,Baumann
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p. 1587 - 1590
(2007/10/03)
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- Synthesis of 2-Phenoxyhexanal and 2-(o-Formylphenoxy)Hexanoic Acid and Its Derivatives
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The paper describes the synthesis of 2-phenoxyhexanal and 2-(o-formylphenoxy)hexanoic acid and its derivatives which are intermediate compounds in the synthesis of new heterocyclic compounds.Key words: 2-phenoxyhexanal, 2-phenoxyhexanoic acid derivatives, 2-butylbenzofurane
- Kwiecien, H.
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p. 661 - 666
(2007/10/02)
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- Novel cyclization to benzofurans in the reaction of alkynyl(p-phenylene) bisiodonium ditriflates with phenoxide anion
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Reaction of alkynyl(p-phenylene)bisiodonium ditriflates (2) with sodium phenoxide in methanol provides 2-substituted benzofurans (3). This result indicates that β-phenoxyalkylidenecarbenes generated by the reaction with phenoxide anion undergo novel intramolecular aromatic C-H insertion to afford benzofurans.
- Kitamura, Tsugio,Zheng, Lei,Taniguchi, Hiroshi,Sakurai, Makoto,Tanaka, Ryuichi
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p. 4055 - 4058
(2007/10/02)
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- CARBON-CARBON BOND FORMATION BY THE REACTION OF ORGANOLITHIUMS WITH α-LITHIATED CYCLIC ENOL ETHERS. STEREOSELECTIVE SYNTHESIS OF β- AND γ-HYDROXY DI- AND TRISUBSTITUTED ALKENES
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α-Lithiation of dihydrofuran, benzofuran, and dihydropyran followed by treatment with various organolithiums stereoselectively produces in good yields the corresponding ring-opened (E)-alkenyllithiums, i. e., (E)-β(or γ)-hydroxy-ω-alkenyl-ω-lithioalkenes, the lithium atom of which can be readily replaced with H, D, or C groups, such as CO2 or Me.
- Nguyen, Thinh,Negishi, Ei-ichi
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p. 5903 - 5906
(2007/10/02)
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The intramolecular condensation of o-acyloxybenzylidenetriphenylphosphoranes leads to acylated products in t-BuOH and to benzofurans in toluene. Mechanistic aspects are discussed. A general method is described for the synthesis of benzofurans from o-cresols, o-hydroxybenzylic alcohols, and deactivated phenols.
- Hercouet,Le Corre
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p. 2867 - 2873
(2007/10/02)
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- Process for the synthesis of derivatives of the benzofuran, chromene and isochromene type
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The invention relates to a process for the production of therapeutic compounds of the benzofuran, chromene and isochromene type of the general formula; STR1 in which formula, STR2 R1 and R3 =H, lower alkyl, aralkyl or cycloalkyl R2 =H or an organic radical and when D= STR3 R1 and R3 may represent an organic radical. The process comprising the cyclization in the liquid phase and in the presence of a base a compound of the formula; STR4 in which formula; R'=an alkyl, aryl or aralkyl radical and X- =an anion.
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