- Metal-Free Radical Annulation of Oxygen-Containing 1,7-Enynes: Configuration-Selective Synthesis of (E)-3-((Arylsulfonyl)methyl)-4-Substituted Arylidenechromene Derivatives
-
A novel strategy for the synthesis of (E)-3-((arylsulfonyl)methyl)-4-substituted benzylidenechromene derivatives via a metal-free radical annulation reaction of oxygen-containing 1,7-enynes with thiosulfonates has been developed. The reaction shows broad substrate scope, wide functional group tolerance, and moderate to excellent yields. Moreover, thiosulfonates were well driven to achieve the bifunctionalization reaction of oxo-1,7-enynes which derived from aliphatic alkynes. In addition, the (E)-configuration of the products was highly controlled by the structure of 1,7-enyne.
- Bian, Mouwang,Dai, Lei,Mao, Kaimin,Rong, Liangce,Wang, Chang,Yu, Qiuyu,Zhang, Jinghang
-
supporting information
p. 218 - 224
(2021/01/13)
-
- A Facile Construction of Bisheterocyclic Methane Scaffolds through Palladium-Catalyzed Domino Cyclization
-
A convenient palladium-catalyzed domino cyclization reaction for the construction of bis(benzofuranyl)methane scaffolds bearing an all-carbon quaternary center has been described. In the cascade process, one C(sp2)—O bond, two C(sp2)—C(sp3) bonds as well as two benzofuran rings are formed in a single synthetic sequence. The approach shows wide scope of substrates and good functional-group tolerance. Moreover, this methodology is successfully extended to the synthesis of benzofuranyl methyl chromane derivatives.
- Qi, Hongbo,Han, Kaiming,Chen, Shufeng
-
supporting information
p. 2699 - 2704
(2021/08/03)
-
- Photocatalyzed Coupling-Cyclization of ortho-Alkynylaryl Vinylethers with Arylsulfonyl Azides
-
A novel visible-light-induced coupling-cyclization of ortho-alkynylaryl vinylethers with arylsulfonyl azides has been described. This transformation provided a concise approach to access C3-exocyclic C=C bond/C2-alkylsulfone-tethered benzofurans via a solvent-leveraged carbosulfonylation and [2 + 2 + 3] cyclization. Primary mechanistic studies demonstrated that THF belongs to a crucial H atom source.
- Chen, Fengjuan,Huang, Xiang,Yang, Can,Jiang, Huanfeng,Zeng, Wei
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p. 14572 - 14585
(2021/10/25)
-
- Copper-catalyzed (4+1) and (3+2) cyclizations of iodonium ylides with alkynes
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The copper(ii)-catalyzed (4+1) cyclizations and copper(i)-catalyzed (3+2) cycloadditions of iodonium ylides and alkynes were successfully developed by employing efficient and safe iodonium ylides instead of traditional diazo compounds. Highly functionaliz
- Liang, Hao,He, Xiaobo,Zhang, Yaqi,Chen, Bin,Ouyang, Jia-Sheng,Li, Yongsu,Pan, Bendu,Subba Reddy, Chitreddy V.,Chan, Wesley Ting Kwok,Qiu, Liqin
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p. 11429 - 11432
(2020/10/12)
-
- Synthesis of diarylalkanes through an intramolecular/intermolecular addition sequence by auto-tandem catalysis with strong Br?nsted base
-
An auto-tandem catalysis with a strong Br?nsted base enabled the synthesis of diarylalkanes containing a benzofuran moiety. Potassiumtert-butoxide efficiently catalyzed both the intramolecular cyclization of less acidicortho-alkynylaryl benzyl ethers and the following intermolecular addition of diarylmethanes to styrenes, demonstrating the high potential of the catalysis in organic synthesis.
- Kondoh, Azusa,Ma, Chaoyan,Terada, Masahiro
-
supporting information
p. 10894 - 10897
(2020/10/02)
-
- Borylative Heterocyclization without Air-Free Techniques
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In contrast to previously reported borylative heterocyclization methods, a reaction here proceeds without air-free techniques to access synthetically useful borylated thiophenes, benzothiophenes, and isocoumarins. A comparison of stability/decomposition rates in air of several catecholboronic ester (Bcat) compounds derived from different heterocycle cores showed a strong dependence on the heterocycle structure. Lessons learned from this comparison were then harnessed for the development of borylative heterocyclization reactions under ambient-atmosphere conditions and with wet solvent. In contrast to literature reports suggesting general moisture sensitivity, a subset of Bcat products resulting from this technique were chromatography-stable and directly isolable, obviating the requirement for an extra synthetic transformation into more stable boron species, such as pinacolboronic esters (Bpin), for isolation. The isolated Bcat products were amenable to various downstream functionalization reactions, including reactions that were not accessible with their better-known Bpin counterparts, showing the complementarity of Bcat reaction partners and expanding their known chemistry. These results suggest the value of conceptual revisitation of substitution and solvent influence on stability and isolability of organo-Bcat compound classes and lay the groundwork for development of additional practical borylative methods in air.
- Blum, Suzanne A.,Gao, Chao,Nakao, Shuichi
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p. 10350 - 10368
(2020/09/23)
-
- One-Pot Generation of Benzynes from Phenols: Formation of Primary Anilines by the Deoxyamination of Phenols
-
Benzynes were selectively generated in situ from phenols and trapped regioselectively with potassium hexamethyldisilazide to form primary anilines following acidic workup. The direct conversion of a phenolic hydroxyl group into a free amino group is a useful method for the preparation of primary aryl amines that are hard to synthesize by using coupling reactions involving phenol derivatives with ammonia. Whereas reactions of ortho- and meta-substituted phenols produced meta-substituted anilines exclusively, those of para-substituted phenols provided ortho-silylanilines.
- Akai, Shuji,Ikawa, Takashi,Masuda, Shigeaki
-
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- Thermal [2 + 2]-cycloaddition between silylalkynes and allenylphenols followed by the nucleophilic addition of water: Metal-free and economical synthesis of arylcyclobutenals
-
Herein, we report an unprecedented thermal [2 + 2]-cycloaddition between silylalkynes and allenylphenols to form an aromatizing cyclobutachromene intermediate, followed by the nucleophilic addition of water to yield functionalized arylcyclobutenals. This reaction is atom- and pot-economical because all the atoms contained in the starting material are retained in the final product, no other reactants are required, and it proceeds in one-pot.
- Ohno, Shohei,Avena, Ramon Francisco,Aoyama, Hiroshi,Fujioka, Hiromichi,Arisawa, Mitsuhiro
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p. 1220 - 1228
(2020/03/11)
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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)
-
- Application of compound containing trifluoromethyl indeno benzo six-membered heterocyclic structure in prevention and treatment of plant diseases and pests
-
The invention relates to application of a compound containing a trifluoromethyl indeno benzo six-membered heterocyclic structure in prevention and treatment of plant diseases and pests. The significance of each group in the formula is shown in the specifi
- -
-
Paragraph 0044-0046
(2020/07/02)
-
- Light-Induced Mechanistic Divergence in Gold(I) Catalysis: Revisiting the Reactivity of Diazonium Salts
-
In a systematic study of the Au-catalyzed reaction of o-alkynylphenols with aryldiazonium salts, we find that essentially the same reaction conditions lead to a change in mechanism when a light source is applied. If the reaction is carried out at room temperature using a AuI catalyst, the diazonium salt undergoes electrophilic deauration of a vinyl AuI intermediate and provides access to substituted azobenzofurans. If the reaction mixture is irradiated with blue LED light, C?C bond formation due to N2-extrusion from the diazonium salt is realized selectively, using the same starting materials without the need for an additional photo(redox) catalyst under aerobic conditions. We report a series of experiments demonstrating that the same vinyl AuI intermediate is capable of producing the observed products under photolytic and thermal conditions. The finding that a vinyl AuI complex can directly, without the need for an additional photo(redox) catalyst, result in C?C bond formation under photolytic conditions is contrary to the proposed mechanistic pathways suggested in the literature till date and highlights that the role of oxidation state changes in photoredox catalysis involving Au is thus far only poorly understood and may hold surprises for the future. Computational results indicate that photochemical activation can occur directly from a donor–acceptor complex formed between the vinyl AuI intermediate and the diazonium salt.
- Taschinski, Svenja,D?pp, René,Ackermann, Martin,Rominger, Frank,de Vries, Folkert,Menger, Maximilian F. S. J.,Rudolph, Matthias,Hashmi, A. Stephen K.,Klein, Johannes E. M. N.
-
supporting information
p. 16988 - 16993
(2019/11/13)
-
- Metal-free difunctionalization of alkynes to access tetrasubstituted olefins through spontaneous selenosulfonylation of vinylidene: Ortho -quinone methide (VQM)
-
A metal-free difunctionalization of alkynes to access tetrasubstituted olefins through spontaneous selenosulfonylation of vinylidene ortho-quinone methide (VQM) was described herein. The reaction was conducted under mild conditions without any catalysts or additives. Preliminary mechanism studies revealed that the formation of VQM was the key for this alkyne di-functionalization reaction. The reaction could be applied in the enantioselective asymmetric synthesis of axially chiral styrene. Furthermore, the selenosulfonylation adducts can be transformed into useful naphtho[2,1-b]furan and benzofuran scaffolds.
- Huang, Shengli,Chen, Zhili,Mao, Hui,Hu, Fangli,Li, Dongmei,Tan, Yu,Yang, Fengqing,Qin, Wenling
-
supporting information
p. 1121 - 1129
(2019/02/07)
-
- Ni-Catalyzed Cycloisomerization between 3-Phenoxy Acrylic Acid Derivatives and Alkynes via Intramolecular Cleavage and Formation of the C-O Bond to Give 2,3-Disubstituted Benzofurans
-
Reactions based on transition-metal-catalyzed C-O bond cleavage have attracted much attention as a new synthetic method. Until now, several intermolecular reactions via C-O bond cleavage of aryl ethers, alkenyl ethers, esters, and others have been reported. Here we report an unprecedented C-O bond cleavage of 3-phenoxy acrylic acid derivatives, followed by intramolecular C-O bond formation with alkynes. This reaction gave 2,3-disubstituted benzofurans having useful functional groups-silyl substituents and acrylic acid derivatives- A t the 2- A nd 3-positions, respectively. This report also described theoretical (DFT) insights into the mechanism.
- Ohno, Shohei,Qiu, Jiawei,Miyazaki, Ray,Aoyama, Hiroshi,Murai, Kenichi,Hasegawa, Jun-Ya,Arisawa, Mitsuhiro
-
supporting information
p. 8400 - 8403
(2019/10/14)
-
- Photoredox Decarboxylative Alkylation/(2+2+1) Cycloaddition of 1,7-Enynes: A Cascade Approach Towards Polycyclic Heterocycles Using N-(Acyloxy)phthalimides as Radical Source
-
No Abstract. (Figure presented.).
- Correia, José Tiago Menezes,Piva da Silva, Gustavo,André, Elias,Paix?o, Márcio Weber
-
supporting information
p. 5558 - 5564
(2019/09/16)
-
- 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)
-
- Magnetically retrievable N-heterocyclic carbene-silver complex with wingtip ferrocenyl group for Sonogashira coupling
-
A new magnetically retrievable N-heterocyclic carbene-silver complex with wingtip ferrocenyl group has been prepared by multi-step procedure. The formation of complex was confirmed on the basis of analytical techniques such as FT-IR, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-Ray diffraction (XRD), transmission electron microscopy (TEM) and VSM (vibrating sample magnetometer) analysis. The complex was successfully employed as an efficient heterogeneous catalyst for Sonogashira coupling reaction of aryl halides with terminal alkynes. The complex could be separated easily by applying external magnet. The reusability studies revealed that complex can be reused up to eight times without significant decrease in catalytic activity.
- Naikwade, Altafhusen,Bansode, Prakash,Rashinkar, Gajanan
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p. 112 - 122
(2018/05/03)
-
- Copper-Catalyzed Annulation Cascades of Alkyne-Tethered α-Bromocarbonyls with Alkynes: An Access to Heteropolycycles
-
We here describe a new Cu-catalyzed annulation cascade of alkyne-tethered α-bromocarbonyls with common alkynes for the synthesis of various heteropolycycle frameworks, including 1H-benzo[de]quinolin-2(3H)-ones, 4H-dibenzo[de,g]quinolin-5(6H)-one, and benzo[de]chromen-2(3H)-one, which were constructed with high selectivity. This was achieved by two-component annulation cascades, rather than atom-transfer radical cyclization (ATRC), with alkyne-tethered α-bromocarbonyls for one-step accessing heteropolycycles via C-Br bond split, intramolecular cyclization, intermolecular [4 + 2] annulation, and aryl C(sp2)-H functionalization cascades.
- Liu, Bang,Yu, Jiang-Xi,Li, Yang,Li, Jin-Heng,He, De-Liang
-
supporting information
p. 2129 - 2132
(2018/04/30)
-
- Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water
-
Generally, oxy-trifluoromethylation in olefins is achieved using oxidants and transition metal catalysts. However, labile olefins remain unexplored due to their incompatibility with harsh reaction conditions. Here, unprecedented light-induced oxidant and metal-free tandem radical cyclization-trifluoromethylation and dehydrogenative oxygenation of 1,6-enynes have been achieved using a photoredox catalyst, CF3SO2Na, and phenanthrene-9,10-dione (PQ), Langlois' reagent (CF3SO2Na) and water as the oxygen source. This benign protocol allows for access to various CF3-containing C3-aryloyl/acylated benzofurans, benzothiophenes, and indoles. Moreover, the oxidized undesired products, which are inherently formed by the cleavage of the vinylic carbon and heteroatom bond, have been circumvented under oxidant free conditions. The mechanistic investigations by UV-visible and ESR spectroscopy, electrochemical studies, isotope labelling and density functional theory (DFT) suggest that light induced PQ produced a CF3 radical from CF3SO2Na. The generated CF3 radical adds to the alkene, followed by cyclization, to provide a vinylic radical that transfers an electron to PQ and generates a vinylic cation. Alternatively, electron transfer may occur from the CF3-added alkene moiety, forming a carbocation, which would undergo cationic cyclization to generate a vinylic carbocation. The subsequent addition of water to the vinylic cation, followed by the elimination of hydrogen gas, led to the formation of trifluoromethylated C3-aryloyl/acylated heterocycles.
- Jana, Sadhan,Verma, Ajay,Kadu, Rahul,Kumar, Sangit
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p. 6633 - 6644
(2017/08/29)
-
- Heterotetracenes: Flexible Synthesis and in Silico Assessment of the Hole-Transport Properties
-
Thienoacenes and furoacenes are among the most frequent molecular units found in organic materials. The efficient synthesis of morphologically different heteroacenes and the rapid determination of their solid-state and electronic properties are still challenging tasks, which slow down progress in the development of new materials. Here, we report a flexible and efficient synthesis of unprecedented heterotetracenes based on a platinum- and gold-catalyzed cyclization–alkynylation domino process using EthynylBenziodoXole (EBX) hypervalent iodine reagents in the key step. The proof-of-principle in silico estimation of the synthesized tetracenes’ charge transport properties reveals their strong dependence on both the position and nature of the heteroatoms in the ring system. A broad range of mobility is predicted, with some compounds displaying performance potentially comparable to that of state-of-the-art electronic organic materials.
- Li, Yifan,Gryn'ova, Ganna,Saenz, Felipe,Jeanbourquin, Xavier,Sivula, Kevin,Corminboeuf, Clémence,Waser, Jér?me
-
supporting information
p. 8058 - 8065
(2017/06/19)
-
- Cycloisomerization between Aryl Enol Ether and Silylalkynes under Ruthenium Hydride Catalysis: Synthesis of 2,3-Disubstituted Benzofurans
-
Metal-catalyzed cycloisomerization reactions of 1,n-enynes have become conceptually and chemically attractive processes in the search for atom economy, which is a key subject of current research. However, metal-catalyzed cycloisomerization between aryl enol ether and silylalkynes has not been developed. The ruthenium hydride complex catalyzed cycloisomerization between aryl enol ether and silylalkynes is reported to give benzofurans having useful functional groups, vinyl and trimethylsilylmethyl, on the 2- and 3-positions, respectively.
- Ohno, Shohei,Takamoto, Kohei,Fujioka, Hiromichi,Arisawa, Mitsuhiro
-
supporting information
p. 2422 - 2425
(2017/05/12)
-
- Copper-Iodide- and Diorganyl-Diselenide-Promoted Cyclization of 2-Alkynylphenols: Alternative Approach to 3-Organoselanylbenzo[b]furans
-
This paper describes an alternative method for the synthesis of 3-organoselanylbenzo[b]furans through the intramolecular cyclization of 2-alkynylphenols promoted by copper iodide and diorganyl diselenides. The cyclization reactions were carried out at roo
- Kazmierczak, Jean C.,Recchi, Ana M. S.,Gritzenco, Fabiane,Balbom, Everton B.,Barcellos, Thiago,Speran?a, Adriane,Godoi, Benhur
-
supporting information
p. 6382 - 6389
(2017/12/01)
-
- Visible-light-enhanced photocatalytic Sonogashira reaction over silicon carbide supported Pd nanoparticles
-
Sonogashira reaction of aryl halides with terminal alkynes can be realized by a visible-light-driven heterogeneous catalytic route using silicon carbide supported Pd nanoparticles as the catalyst under copper-, and ligand-free conditions. Under the irradi
- Wang, Bing,Guo, Xiaoning,Jin, Guoqiang,Guo, Xiangyun
-
-
- Synthesis of substituted benzofurans and indoles by Zn-catalyzed tandem Sonogashira-cyclization strategy
-
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
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p. 536 - 540
(2017/01/16)
-
- Method for synthesizing multi-substituted alkyne
-
The invention discloses a method for synthesizing multi-substituted alkyne, relates to the technical field of synthesis of multi-substituted alkyne and provides a method for synthesizing multi-substituted alkyne through terminal alkyne and halide of sp2 type carbon under the catalysis of a polyaniline supported nano-palladium catalyst. According to the method, polyaniline supported nano-palladium is taken as a catalyst, diisopropyl-2-ethyoxyl ethylamine is taken as alkali, and multi-substituted alkyne is directly synthesized in one step through cross coupling. Compared with conventional methods, the method has the advantages that raw materials are simple and easy to obtain, the cost is low, the catalyst is mild, environment-friendly and rich, and a solvent is clean and environment-friendly. Thus, a clean and practical synthesis method is provided for synthesis of such important compounds.
- -
-
Paragraph 0012; 0013; 0022; 0023
(2016/11/24)
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- Gold-Catalyzed Fluorination–Hydration: Synthesis of α-Fluorobenzofuranones from 2-Alkynylphenol Derivatives
-
The AuI-catalyzed fluorination–hydration of 2-alkynylphenol derivatives in the presence of Selectfluor [1-chloromethyl-4-fluoro-1,4-diazoniabicyclo-[2.2.2]octane bis(tetrafluoroborate)] has been developed. This method provides straightforward a
- Wang, Qiang,Jiang, Yu,Sun, Run,Tang, Xiang-Ying,Shi, Min
-
supporting information
p. 14739 - 14745
(2016/10/03)
-
- Kinetic Study of Carbophilic Lewis Acid Catalyzed Oxyboration and the Noninnocent Role of Sodium Chloride
-
In the present study, the oxyboration reaction catalyzed by IPrAuTFA in the presence and absence of NaTFA has been examined with kinetic studies, mass spectrometry, and 1H NMR and 11B NMR spectroscopy. Data from monitoring the reacti
- Johnson, Joel S.,Chong, Eugene,Tu, Kim N.,Blum, Suzanne A.
-
p. 655 - 662
(2016/04/20)
-
- Synthesis of Substituted Furan/Pyrrole-3-carboxamides through a Tandem Nucleopalladation and Isocyanate Insertion
-
Access to furanyl- and pyrrolyl-3-carboxamides from readily available 3-alkyne-1,2-diols and 1-amino-3-alkyn-2-ols using isocyanate as amido surrogate is demonstrated. The approach constitutes a successful unprecedented combination of heteropalladation an
- Rajesh, Manda,Puri, Surendra,Kant, Ruchir,Reddy, Maddi Sridhar
-
supporting information
p. 4332 - 4335
(2016/10/06)
-
- A Palladium-Catalyzed Domino Approach to 2,3-Disubstituted Benzofurans via an Intermolecular Carbopalladation/C(sp3)?H Functionalization/Isomerization Sequence
-
A palladium-catalyzed domino strategy has been developed for the synthesis of 2,3-disubstituted benzofuran derivatives. This cascade reaction sequence involves intermolecular carbopalladation and C(sp3)?H functionalization followed by isomerization. (Figure presented.).
- Boominathan, Siva Senthil Kumar,Hou, Ruei-Jhih,Hu, Wan-Ping,Huang, Po-Jui,Wang, Jeh-Jeng
-
supporting information
p. 2984 - 2989
(2016/09/16)
-
- Scope and limitations of a DMF bio-alternative within Sonogashira cross-coupling and Cacchi-type annulation
-
Pd-catalysed C-C bond formation is an essential tool within the pharmaceutical and agrochemical industries. Many of these reactions rely heavily on polar aprotic solvents; however, despite their utility, these solvents are incompatible with the drive towards more sustainable chemical synthesis. Herein, we describe the scope and limitations of an alternative to DMF derived from renewable sources (Cyrene) in Sonogashira cross-coupling and Cacchi-type annulations.
- Wilson, Kirsty L.,Kennedy, Alan R.,Murray, Jane,Greatrex, Ben,Jamieson, Craig,Watson, Allan J. B.
-
supporting information
p. 2005 - 2011
(2016/10/05)
-
- Radical Cascade Cyclization: Reaction of 1,6-Enynes with Aryl Radicals by Electron Catalysis
-
The radical cascade cyclization of various 1,6-enynes with aryl radicals by electron catalysis under metal-free reaction conditions was explored. Readily available anilines were used as radical precursors, and the reactions proceeded in the absence of any transition metal. These cascades comprise three C–C bond formations, which provide polycyclic structures with extended π-systems. The photophysical properties of some of these novel compounds were investigated, and a plausible reaction mechanism is proposed.
- Xuan, Jun,Gonzalez-Abradelo, Dario,Strassert, Cristian Alejandro,Daniliuc, Constantin-Gabriel,Studer, Armido
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supporting information
p. 4961 - 4964
(2016/10/26)
-
- Enantioselective intramolecular cyclization of alkynyl esters catalyzed by a chiral Br?nsted base
-
An enantioselective intramolecular cyclization reaction of alkynyl esters was developed, which employs a Br?nsted base catalyst generated in situ from a chiral Schiff base and t-BuOK. This reaction is a rare example of the enantioselective intramolecular addition of simple ester enolates to alkynes under Br?nsted base catalysis.
- Kondoh, Azusa,Tran, Hoa Thi Quynh,Kimura, Kyoko,Terada, Masahiro
-
supporting information
p. 5726 - 5729
(2016/05/19)
-
- Dual Photoredox/Gold Catalysis Arylative Cyclization of o-Alkynylphenols with Aryldiazonium Salts: A Flexible Synthesis of Benzofurans
-
A new method for the arylative cyclization of o-alkynylphenols with aryldiazonium salts via dual photoredox/gold catalysis is described. The reaction proceeds smoothly at room temperature in the absence of base and/or additives and offers an efficient app
- Xia, Zhonghua,Khaled, Omar,Mouriès-Mansuy, Virginie,Ollivier, Cyril,Fensterbank, Louis
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p. 7182 - 7190
(2016/08/30)
-
- Rhodium(III)-Catalyzed Cascade Cyclization/Electrophilic Amidation for the Synthesis of 3-Amidoindoles and 3-Amidofurans
-
A rhodium(III)-catalyzed cascade cyclization/electrophilic amidation using N-pivaloyloxylamides as the electrophilic nitrogen source has been developed. This protocol provides an efficient route for the synthesis of 3-amidoindoles and 3-amidofurans under mild conditions with good functional group tolerance. The synthetic utility of this reaction has been demonstrated through the derivatization of the 3-amidoindoles to several heterocycle-fused indoles.
- Hu, Zhiyong,Tong, Xiaofeng,Liu, Guixia
-
supporting information
p. 2058 - 2061
(2016/06/01)
-
- Efficient Sonogashira and Suzuki-Miyaura coupling reaction catalyzed by Pd-Nanoparticles
-
The Pd nano particles were electrochemically deposited on nafion-graphene. They showed excellent catalytic activity towards Sonogashira and Suzuki-Miyaura cross-coupling reaction. Benzenediazonium salts were used as alternative to aromatic halide. The developed protocol offers recyclability, easy workups with short reaction time and good-to-excellent product yield. [Figure not available: see fulltext.]
- Balsane, Kishor E.,Shendage, Suresh S.,Nagarkar, Jayashree M.
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p. 425 - 431
(2015/05/13)
-
- Well-Defined Noble Metal Single Sites in Zeolites as an Alternative to Catalysis by Insoluble Metal Salts
-
Insoluble precious metal chlorides in polymeric form (i.e., PtCl2, PdCl2, AuCl, RhCl3) are commonly used as catalysts for a plethora of organic reactions in solution. Here we show that only the minor soluble fraction of these precious metal chlorides (typically 5-30%) is catalytically active for the hydroamination, hydroalkoxylation, hydrosilylation, and cycloisomerization of alkynes and alkenes, and that the resting insoluble metal is catalytically useless. To circumvent this waste of precious metal and follow a rational design, we generate here well-dispersed Pt(II) and Pd(II) single sites on zeolite Y, with an exquisite control of the Lewis acidity, to catalyze different hydroaddition reactions to alkynes and alkenes with up to 104 catalytic cycles (at least 2 orders of magnitude superior to precious metal chlorides) and with high isolated yields (82-99%, >15 examples).
- Rubio-Marqués, Paula,Rivero-Crespo, Miguel A.,Leyva-Pérez, Antonio,Corma, Avelino
-
supporting information
p. 11832 - 11837
(2015/09/28)
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- A concise approach for the synthesis of 3-iodoindoles and 3-iodobenzo[b]furans via Ph3P-catalyzed iodocyclization
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A variety of 3-iodoindole and 3-iodobenzo[b]furan derivatives were conveniently prepared from the corresponding 2-alkynylanilines and 2-alkynylphenols through Ph3P-catalyzed iodocyclization in the presence of N-iodosuccinimide (NIS). This proto
- Li, Yin-Long,Li, Jian,Yu, Sheng-Nan,Wang, Ji-Bo,Yu, Yan-Min,Deng, Jun
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supporting information
p. 8271 - 8277
(2015/10/05)
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- Expanded-ring N-heterocyclic carbenes efficiently stabilize gold(I) cations, leading to high activity in π-acid-catalyzed cyclizations
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A series of six- and seven-membered expanded-ring N-heterocyclic carbene (er-NHC) gold(I) complexes has been synthesized using different synthetic approaches. Complexes with weakly coordinating anions [(er-NHC)AuX] (X -=BF4-, NTf2-, OTf -) were generated in solution. According to their 13C NMR spectra, the ionic character of the complexes increases in the order X -=Cl-2--4-. Additional factors for stabilization of the cationic complexes are expansion of the NHC ring and the attachment of bulky substituents at the nitrogen atoms. These er-NHCs are bulkier ligands and stronger electron donors than conventional NHCs as well as phosphines and sulfides and provide more stabilization of [(L)Au+] cations. A comparative study has been carried out of the catalytic activities of five-, six-, and seven-membered carbene complexes [(NHC)AuX], [(Ph3P)AuX], [(Me2S)AuX], and inorganic compounds of gold in model reactions of indole and benzofuran synthesis. It was found that increased ionic character of the complexes was correlated with increased catalytic activity in the cyclization reactions. As a result, we developed an unprecedentedly active monoligand cationic [(THD-Dipp)Au]BF4 (1,3-bis(2,6-diisopropylphenyl) -3,4,5,6-tetrahydrodiazepin-2-ylidene gold(I) tetrafluoroborate) catalyst bearing seven-membered-ring carbene and bulky Dipp substituents. Quantitative yields of cyclized products were attained in several minutes at room temperature at 1 mol% catalyst loadings. The experimental observations were rationalized and fully supported by DFT calculations. What a difference a ring makes: Expanded-ring N-heterocyclic carbenes (er-NHC) surpass their five-membered ring counterparts, as well as Ph3P and Me2S, in the stabilization of cationic gold(I) species due to increased steric protection and electron-donating properties. A monoligand cationic [(THD-Dipp)Au]BF 4 (Dipp=2,6-diisopropylphenyl) complex bearing a seven-membered ring carbene and bulky Dipp substituents exhibits unprecedentedly high catalytic activity in indole and benzofuran synthesis (see scheme).
- Morozov, Oleg S.,Lunchev, Andrey V.,Bush, Alexander A.,Tukov, Aleksandr A.,Asachenko, Andrey F.,Khrustalev, Victor N.,Zalesskiy, Sergey S.,Ananikov, Valentine P.,Nechaev, Mikhail S.
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supporting information
p. 6162 - 6170
(2014/05/20)
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- Alkoxyboration: Ring-closing addition of B-O σ bonds across alkynes
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For nearly 70 years, the addition of boron-X σ bonds to carbon-carbon multiple bonds has been employed in the preparation of organoboron reagents. However, the significantly higher strength of boron-oxygen bonds has thus far precluded their activation for addition, preventing a direct route to access a potentially valuable class of oxygen-containing organoboron reagents for divergent synthesis. We herein report the realization of an alkoxyboration reaction, the addition of boron-oxygen σ bonds to alkynes. Functionalized O-heterocyclic boronic acid derivatives are produced using this transformation, which is mild and exhibits broad functional group compatibility. Our results demonstrate activation of this boron-O σ bond using a gold catalysis strategy that is fundamentally different from that used previously for other boron addition reactions.
- Hirner, Joshua J.,Faizi, Darius J.,Blum, Suzanne A.
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supporting information
p. 4740 - 4745
(2014/04/17)
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- Copper- and Phosphane-Free Sonogashira Coupling of Arenediazonium o-Benzenedisulfonimides
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Arenediazonium o-benzenedisulfonimides can be used as efficient reagents in Sonogashira coupling reactions. In this work, reactions were carried out in DMSO under very mild conditions (without copper or phosphanes), and gave rise to arylated alkynes in good to excellent yields (25 examples, average yield 83 %). o-Benzenedisulfonimide could be recovered from all the reactions in yields of >80 %, so it could be recycled for the preparation of other diazonium salts. Mechanistic insights revealed the fundamental roles of DMSO and the anion of o-benzenedisulfonimide in the formation of the catalyst, and also the importance of DMSO in the catalytic cycle. The Sonogashira coupling between are diazonium o-benzenedisulfonimides and terminal alkynes is a powerful method for the formation of arylated alkynes. No copper, phosphanes, bases, or co-catalysts are needed. Mechanistic insights highlighted the fundamental roles of DMSO and o-benzenedisulfonimide in the formation of the catalyst, and also the important role of DMSO in the catalytic cycle.
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano
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p. 598 - 605
(2015/10/05)
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- Copper- and phosphane-free sonogashira coupling of arenediazonium o-benzenedisulfonimides
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Arenediazonium o-benzenedisulfonimides can be used as efficient reagents in Sonogashira coupling reactions. In this work, reactions were carried out in DMSO under very mild conditions (without copper or phosphanes), and gave rise to arylated alkynes in good to excellent yields (25 examples, average yield 83 %). o-Benzenedisulfonimide could be recovered from all the reactions in yields of >80 %, so it could be recycled for the preparation of other diazonium salts. Mechanistic insights revealed the fundamental roles of DMSO and the anion of o-benzenedisulfonimide in the formation of the catalyst, and also the importance of DMSO in the catalytic cycle. The Sonogashira coupling between are diazonium o-benzenedisulfonimides and terminal alkynes is a powerful method for the formation of arylated alkynes. No copper, phosphanes, bases, or co-catalysts are needed. Mechanistic insights highlighted the fundamental roles of DMSO and o-benzenedisulfonimide in the formation of the catalyst, and also the important role of DMSO in the catalytic cycle. Copyright
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano
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p. 598 - 605
(2014/02/14)
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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
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supporting information
p. 3798 - 3806
(2014/05/20)
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- Tandem gold-catalyzed hydrosilyloxylation-aldol and -Mannich reaction with alkynylaryloxysilanols in 6-exo mode
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The tandem gold-catalyzed hydrosilyloxylation-aldol and hydrosilyloxylation-Mannich reactions were developed through the formation of an enol silyl ether catalytically generated in situ from alkynylaryloxysilanols in the 6-exo mode in one reaction vessel. Copyright
- Lee, Euichul,Ryu, Taekyu,Park, Youngchul,Park, Sangjune,Lee, Phil Ho
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p. 1585 - 1596
(2013/06/27)
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- Efficient microwave-assisted one-pot three-component synthesis of 2,3-disubstituted benzofurans under Sonogashira conditions
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An efficient one-pot method for the synthesis of 2,3-disubstituted benzo[b]furans from commercially available 2-iodophenols, terminal acetylenes and aryl iodides has been developed utilizing Sonogashira reaction conditions. After an initial Sonogashira coupling of the 2-iodophenol with the terminal alkyne, cyclization involving the aryl iodide provides the 2,3-disubstituted benzo[b]furan in good to excellent yields. The use of microwave irradiation shortens the reaction times and minimizes the side products. This methodology is especially useful for the construction of libraries of highly substituted benzo[b]furans and their analogues.
- Markina, Nataliya A.,Chen, Yu,Larock, Richard C.
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p. 2701 - 2713
(2013/03/28)
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- Potassium tert-butoxide promoted annulation of 2-alkynylphenyl propargyl ethers: Selective synthesis of benzofuran and 12H-benzoannulene derivatives
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We present here our results on potassium tert-butoxide promoted annulation reactions of 2-alkynylphenyl propargyl ethers to give two different types of heterocycles: 3-benzyl-2-alkynylbenzofurans and 12H-benzoannulenbenzo[b]furans. A series of functionalized 2-alkynylphenyl propargyl ethers were efficiently cyclized by potassium tert-butoxide to the corresponding products. The optimized reaction conditions tolerated a large variety of functional groups, including electron-rich, electron-poor, and N-heterocyclic substrates. Selective product formation was obtained by controlling the solvent and temperature. When THF was used at room temperature, 3-benzyl-2-alkynylbenzofuran derivatives were exclusively obtained, while the use of DMF at 60 C gave selectively 12H-benzoannulen[b]benzofurans.
- Grimaldi, Tamiris B.,Back, Davi F.,Zeni, Gilson
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p. 11017 - 11031
(2013/11/19)
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- Gold and palladium combined for the Sonogashira coupling of aryl and heteroaryl halides
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A highly efficient gold and palladium combined methodology for the Sonogashira coupling of a wide array of electronically and structurally diverse aryl and heteroaryl halides is described. The orthogonal reactivity of the two metals shows high selectivity and extreme functional group tolerance in Sonogashira coupling. A brief mechanistic study reveals that the gold acetylide intermediate enters into the palladium catalytic cycle at the transmetalation step. Georg Thieme Verlag Stuttgart.New York.
- Panda, Biswajit,Sarkar, Tarunk.
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p. 817 - 829
(2013/04/10)
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- A highly efficient BF3·Et2O-catalysed intramolecular [3+2] cycloaddition for the synthesis of 3,4- dihydrobenzopyrano[3,4-c]pyrazoles
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A highly efficient BF3·Et2O catalysed intramolecular [3+2] cycloaddition of tosylhydrazone with alkyne has been developed, and a variety of potentially bioactive 1,8-disubstituted-3,4- dihydrobenzopyrano[3,4-c]pyrazoles 7 were obtained with good to excellent yields of up to 93%.
- Wang, Wei-Liang,Feng, Yu-Lan,Gao, Wen-Qiang,Luo, Xiaoyan,Deng, Wei-Ping
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p. 1687 - 1690
(2013/03/14)
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- Gold-catalyzed cyclizations of (o-alkynyl)phenoxyacrylates with external nucleophiles: Regio-and stereoselective synthesis of functionalized benzo[b]oxepines
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A catalytic approach to benzo[b]oxepines with high stereoselectivity by Au-catalyzed cyclization of (o-alkynyl)phenoxyacrylates with various nucleophiles under mild reaction conditions has been developed. Notably, the use of vinyl ether instead of alcohol could afford the same benzoxepines. The reaction may proceed by Au-catalyzed oligomerization of vinyl ether to release the alcohol, which then reacts with (o-alkynyl)phenoxyacrylates to furnish the benzoxepines.
- Liu, Jun,Liu, Yuanhong
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supporting information
p. 4742 - 4745,4
(2020/09/16)
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- A concise route to dihydrobenzo[b]furans: Formal total synthesis of (+)-lithospermic acid
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A sequence of Sonogashira coupling, Pd(II)-catalyzed carbonylative annulation, and benzofuran reduction (Mg, MeOH, NH4Cl) provides a convergent and modular synthetic route to trans-2-aryl-2,3-dihydrobenzo[b]furan- 3-carboxylates, which are a structural feature of numerous biologically active natural products. This versatile strategy was applied to the formal total synthesis of the anti-HIV natural product (+)-lithospermic acid.
- Fischer, Joshua,Savage, G. Paul,Coster, Mark J.
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supporting information; experimental part
p. 3376 - 3379
(2011/09/12)
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- Rhodium-catalyzed olefin isomerization/enantioselective intramolecular alder-ene reaction cascade
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The olefin isomerization/enantioselective intramolecular Alder-ene reaction cascade was achieved by using a cationic rhodium(I)/(R)-BINAP complex as a catalyst. A variety of substituted dihydrobenzofurans and dihydronaphthofurans were obtained from phenol
- Okamoto, Ryuichi,Okazaki, Eri,Noguchi, Keiichi,Tanaka, Ken
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p. 4894 - 4897
(2011/11/29)
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