- Hexafluoroisopropanol as solvent and promotor in the Paal-Knorr synthesis of N-substituted diaryl pyrroles
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An additive-free synthesis of challenging N-substituted aryl pyrroles from the often poorly soluble corresponding 1,4-diketones by means of the Paal-Knorr pyrrole synthesis is reported, which makes use of the unique properties of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as a solvent and reaction promotor. Our procedure offers simple execution and purification as well as easy scale-up and can be applied in the Paal-Knorr synthesis of a large number of structurally diverse pyrroles including the synthetically challenging tetra- and penta-substituted pyrroles in moderate to excellent yields. HFIP can also be used as solvent in the Paal-Knorr synthesis of furans and thiophenes; however, the solvent effect is more pronounced in synthesis of pyrroles.
- Schirmacher, Robert H.E.,R?sch, Daniel,Thomas, Franziska
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- Aerobic Oxidative Dehydrogenation of Ketones to 1,4-Enediones
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An efficient and unprecedented strategy for the synthesis of 1,4-enediones from saturated ketones has been developed via palladium-catalyzed oxidative dehydrogenation. The protocol employs molecular oxygen as the sole oxidant and represents an atom- and step-economic process. The approach showed broad substrate scope, good functional group tolerance, and complete E-stereoselectivity. The reaction mechanism has been investigated through deuterium-labeling experiments and intermediate experiments.
- Zhao, Bao-Yin,Zhang, Xing-Long,Guo, Rui-Li,Wang, Meng-Yue,Gao, Ya-Ru,Wang, Yong-Qiang
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supporting information
p. 1216 - 1221
(2021/02/20)
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- Method for preparing furan compound from brominated arone
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The invention provides a method for synthesizing a furan compound by taking brominated arone and methyl ketone or cyclic ketone as raw materials and directly reacting under the action of tetraisopropyl titanate. The method comprises the following steps: under the protection of inert gas, stirring and heating a reaction mixture of methyl ketone or cyclic ketone and bromo-arone, and then adding tetraisopropyl titanate for reaction; and after the reaction is finished, separating and purifying the obtained reaction mixture to obtain the polysubstituted furan compound. The synthesis method provided by the invention has the advantages of easily available raw materials, low cost, simple operation and easy control, no solvent, good substrate universality and functional group compatibility, and is suitable for industrial mass production.
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Page/Page column 5
(2021/06/13)
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- Reaction of Lithiated Propargyl Ethers with Carbonyl Compounds-A Regioselective Route to Furan Derivatives
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The deprotonation of 3-Aryl-substituted alkyl propargyl ethers with n-butyllithium provides an ambident anion that reacts with carbonyl compounds to provide mixtures of γ-substituted products with alkoxyallene substructure and of α-substituted propargyl ethers. The ratio of the two product types strongly depends on the solvent: in diethyl ether the γ-substituted products predominate whereas the more polar tetrahydrofuran favors the α-Adducts. The primary addition products undergo 5-endo-trig or 5-endo-dig cyclizations under various reaction conditions to afford isomeric furan derivatives. The highest selectivity in favor of α-substituted products was achieved by employing a MOM-protected propargyl ether. During the protonation step no evidence for a proton shift leading to an isomeric allenyl anion was found. A brief mechanistic discussion tries to rationalize the observed regio? selectivities.
- Linder, Igor,Klemme, Robby,Reissig, Hans-Ulrich
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p. 765 - 774
(2020/11/13)
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- Bifunctional phosphine ligand-enabled gold-catalyzed direct cycloisomerization of alkynyl ketones to 2,5-disubstituted furans
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An efficient synthesis of 2,5-disubstituted furans directly from alkynyl ketones has been developed via tandem gold(i)-catalyzed isomerization of alkynyl ketones to allenyl ketones and cycloisomerization. The key to the success of this chemistry is the use of a biphenyl-2-ylphosphine ligand featuring a critical remote tertiary amino group.
- Hu, Xiaojun,Zhou, Bingwei,Jin, Hongwei,Liu, Yunkui,Zhang, Liming
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supporting information
p. 7297 - 7300
(2020/07/14)
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- Synthesis of 1,4-Dicarbonyl Compounds by Visible-Light-Mediated Cross-Coupling Reactions of α-Chlorocarbonyls and Enol Acetates
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Herein, we report a protocol for visible-light-mediated radical coupling reactions of α-chloroketones and enol acetates to afford 1,4-dicarbonyl compounds, which are important precursors and intermediates in organic synthesis. The reaction involves photoredox-catalyzed activation of the α-chloroketone upon photoelectron transfer, carbon–chlorine bond cleavage, and coupling of the resulting radical with the carbon–carbon double bond of the enol acetate. This mild protocol has a wide substrate scope and moderate to good yields. (Figure presented.).
- Liu, Qiang,Wang, Rui-Guo,Song, Hong-Jian,Liu, Yu-Xiu,Wang, Qing-Min
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supporting information
p. 4391 - 4396
(2020/09/21)
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- Synergistic Activation of Amides and Hydrocarbons for Direct C(sp3)–H Acylation Enabled by Metallaphotoredox Catalysis
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The utilizations of omnipresent, thermodynamically stable amides and aliphatic C(sp3)?H bonds for various functionalizations are ongoing challenges in catalysis. In particular, the direct coupling between the two functional groups has not been realized. Here, we report the synergistic activation of the two challenging bonds, the amide C?N and unactivated aliphatic C(sp3)?H, via metallaphotoredox catalysis to directly acylate aliphatic C?H bonds utilizing amides as stable and readily accessible acyl surrogates. N-acylsuccinimides served as efficient acyl reagents for the streamlined synthesis of synthetically useful ketones from simple C(sp3)?H substrates. Detailed mechanistic investigations using both computational and experimental mechanistic studies were performed to construct a detailed and complete catalytic cycle. The origin of the superior reactivity of the N-acylsuccinimides over other more reactive acyl sources such as acyl chlorides was found to be an uncommon reaction pathway which commences with C?H activation prior to oxidative addition of the acyl substrate.
- Baik, Mu-Hyun,Choi, Seulhui,Hong, Soon Hyeok,Lee, Geun Seok,Won, Joonghee
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supporting information
p. 16933 - 16942
(2020/08/03)
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- A Convoluted Polyvinylpyridine-Palladium Catalyst for Suzuki-Miyaura Coupling and C?H Arylation
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The development of highly active and reusable supported catalysts for Suzuki-Miyaura coupling and catalytic C?H arylation is important for fundamental and applied chemistry, with these reactions being used to produce medical compounds and functional materials. Herein, we found that a mesoporous composite made of a linear poly(4-vinylpyridine) and tetrachloropalladate acted as a dual-mode catalyst for a variety of cross-coupling reactions, with both Pd nanoparticles and a Pd complex catalyst being observed under different conditions. The polyvinylpyridine-palladium composite 1 was readily prepared via the molecular convolution of poly(4-vinylpyridine) and sodium tetrachloropalladate to provide a hardly soluble polymer-metal composite. The Suzuki-Miyaura coupling and the C?H arylation of aryl chlorides and bromides with arylboronic acids, thiophenes, furans, benzene, and anisole proceeded in the presence of 0.004 mol% (40 mol ppm) to 1 mol% Pd of 1 to afford the corresponding coupling products in high yields. Furthermore, the catalyst was reused without an appreciable loss of activity. Pharmaceutical compounds and functional materials were synthesized via the coupling reactions. N2 gas adsorption/desorption analysis indicated that the catalyst had a mesoporous nature, which played a crucial role in the catalysis. In the Suzuki-Miyaura couplings, in situ generated palladium nanoparticles in the polymer matrix were catalytically active, while a polymeric Pd(II) complex was crucial in the C?H arylations. These catalytic species were investigated via XAFS, XPS, far-infrared absorption, and Raman spectroscopies, as well as DFT calculations. (Figure presented.).
- Ohno, Aya,Sato, Takuma,Mase, Toshiaki,Uozumi, Yasuhiro,Yamada, Yoichi M. A.
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supporting information
p. 4687 - 4698
(2020/09/07)
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- Copper Nanoparticles on Ordered Mesoporous Carbon Nitride Support: a Superior Catalyst for Homo- and Cross-Coupling of Terminal Alkynes under Base-Free Conditions
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A novel ordered mesoporous carbon nitride (OMCN) was synthesized as a functionalized support with 2,4,6-trichloro-1,3,5-triazine and benzidine as starting materials in the presence of SBA-15 as a template. Copper nanoparticles were then loaded on the C–N material to achieve a novel nanocomposite catalyst (Cu NPs-OMCN). The nanocomposite was utilized as a highly efficient catalyst for homo- and cross-coupling of terminal alkynes under base-free conditions in ethanol, and various symmetrical and unsymmetrical 1,3-diynes were obtained with good to excellent yields. Moreover, based on this reaction, a one-pot approach to synthesize 2,5-disubstituted thiophenes and furans from terminal alkynes were developed. Furthermore, the heterogeneous catalyst could be recovered and reused conveniently for several times with satisfactory yields.
- Xu, Hang,Wu, Liangying,Tian, Jing,Wang, Jun,Wang, Peng,Niu, Xiyu,Yao, Xiaoquan
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p. 6690 - 6696
(2019/11/02)
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- Ruthenium(ii)-catalyzed chemoselective deacylative annulation of 1,3-diones with sulfoxonium ylides: Via C-C bond activation
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The first successful example of deacylative annulation of 1,3-diones with sulfoxonium ylides was achieved through Ru(ii)-catalyzed C-C bond activation. The excellent chemoselectivity and broad substrate scope render this method a practical and versatile approach for the preparation of (hetero)aryl and alkenyl substituted furans, which are valuable units in many biologically active compounds and functional materials. A preliminary mechanistic study reveals that this process involves a deacylative α-ruthenation to generate key alkyl Ru(ii) intermediates with the release of a benzoic acid fragment.
- Wen, Si,Lv, Weiwei,Ba, Dan,Liu, Jing,Cheng, Guolin
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p. 9104 - 9108
(2019/10/21)
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- A porphyrin porous organic polymer with bicatalytic sites for highly efficient one-pot tandem catalysis
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A novel porphyrin-based porous organic polymer PPOP-1(Pd) with bifunctional catalytic sites was constructed via imine condensation of tetra(4-aminophenyl)porphyrin and acenaphthenequinone. PPOP-1(Pd) containing Pd(ii)-porphyrin and Pd(ii)-α-diimine moieties exhibits excellent catalytic activity and outstanding reusability for tandem catalytic reactions of C-H arylation and Suzuki coupling.
- Dai, Siyuan,Gu, Zhi-Guo,Li, Tao,Li, Yunxing,Liu, Yong,Shen, Rui,Yan, Xiaodong,Zhu, Wei
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supporting information
p. 822 - 825
(2019/01/21)
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- Dual Oxidation State Tandem Catalysis in the Palladium-Catalyzed Isomerization of Alkynyl Epoxides to Furans
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A two-catalyst system consisting of different oxidation states of palladium is described, which mediates the isomerization of alkynyl epoxides to furans. In a process termed dual oxidation state tandem catalysis , a multistep isomerization pathway is delineated in which the different metal oxidation states and ligands play independent mechanistic roles, but which, in combination, enable the use of milder reaction conditions and lower catalyst loadings than a single catalyst in isolation. In the present context, this rare example of a homobimetallic catalytic transformation provides a mild, scalable, and atom-efficient route for furan synthesis.
- Arroniz, Carlos,Chaubet, Guilhem,Anderson, Edward A.
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p. 8290 - 8295
(2018/09/06)
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- Continuous Endoperoxidation of Conjugated Dienes and Subsequent Rearrangements Leading to C-H Oxidized Synthons
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We have investigated the continuous flow photooxidation of several conjugated dienes and subsequent rearrangement using a practical and safe continuous-flow homemade engineered setup. End-to-end approaches involving endoperoxidation, Kornblum-DeLaMare rearrangement, and additional rearrangements are comprehensively detailed with optimization, scope, and scale-up to obtain useful hydroxyenones, furans, and 1,4-dicarbonyl building blocks.
- De Souza, Juliana M.,Brocksom, Timothy J.,McQuade, D.Tyler,De Oliveira, Kleber T.
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p. 7574 - 7585
(2018/06/11)
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- A biosynthetically inspired route to substituted furans using the Appel reaction: Total synthesis of the furan fatty acid F5
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Appel reaction conditions have been harnessed to affect a mild biosynthetically inspired dehydration of endoperoxides to deliver multi-substituted electron rich furans. Unlike traditional dehydrative procedures, this method is metal and acid free, and can be achieved under redox neutral conditions. It is general for a range of aryl and alkyl substituted endoperoxides, and is functional group tolerant. Furthermore, this procedure has been used to deliver an effective total synthesis of the furan fatty acid (FFA) F5.
- Lee, Robert J.,Lindley, Martin R.,Pritchard, Gareth J.,Kimber, Marc C.
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supporting information
p. 6327 - 6330
(2017/07/11)
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- Synthesis and 2D-QSAR studies of neolignan-based diaryl-tetrahydrofuran and -furan analogues with remarkable activity against Trypanosoma cruzi and assessment of the trypanothione reductase activity
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Two series of diaryl-tetrahydrofuran and -furan were synthesised and screened for anti-trypanosomal activity against trypomastigote and amastigote forms of Trypanosoma cruzi, the causative agent of Chagas disease. Based on evidence that modification of a natural product may result in a more effective drug than the natural product itself, and using known neolignan inhibitors veraguensin 1 and grandisin 2 as templates to synthesise simpler analogues, remarkable anti-trypanosomal activity and selectivity were found for 3,5-dimethoxylated diaryl-furan 5c and 2,4-dimethoxylated diaryl-tetrahydrofuran 4e analogues with EC50 0.01 μM and EC50 0.75 μM, respectively, the former being 260-fold more potent than veraguensin 1 and 150-fold better than benznidazole, the current available drugs for Chagas disease treatment. The ability of the most potent anti-trypanosomal compounds to penetrate LLC-MK2 cells infected with T. cruzi amastigotes parasite was tested, which revealed 4e and 5e analogues as the most effective, causing no damage to mammalian cells. In particular, the majority of the derivatives were non-toxic against mice spleen cells. 2D-QSAR studies show the rigid central core and the position of dimethoxy-aryl substituents dramatically affect the anti-trypanosomal activity. The mode of action of the most active anti-trypanosomal derivatives was investigated by exploring the anti-oxidant functions of Trypanothione reductase (TR). As a result, diarylfuran series displayed the strongest inhibition, highlighting compounds 5d-e (IC50 19.2 and 17.7 μM) and 5f-g (IC50 8.9 and 7.4 μM), respectively, with similar or 2-fold higher than the reference inhibitor clomipramine (IC50 15.2 μM).
- Hartmann, Ana Paula,de Carvalho, Marcelo Rodrigues,Bernardes, Lilian Sibelle Campos,de Moraes, Milena Hoehr,de Melo, Eduardo Borges,Lopes, Carla Duque,Steindel, Mario,da Silva, Jo?o Santana,Carvalho, Ivone
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p. 187 - 199
(2017/09/20)
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- A alkynyl dione compound and its synthesis method
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The invention discloses a synthetic method of an alkynyl diketone compound which is shown in a formula (II). The synthetic method comprises the following step: in methylbenzene, at 90 DEG C, carrying out a reaction to obtain the alkynyl diketone compound by using alpha hydroxy-ketone and terminal alkyne as reaction raw materials and oxygen as an oxidizing agent under the effect of a copper catalyst. The synthetic method provided by the invention has the advantages that the reaction is efficient and the yield is high; oxygen is used as the oxidizing agent; the reaction condition is mild and no strong acids or strong bases are needed; cheap metals are used for catalyzing; reaction substrates are easy to prepare; amplified reaction can be further achieved.
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- Aerobic oxidative α-arylation of furans with boronic acids via Pd(II)-catalyzed C-C bond cleavage of primary furfuryl alcohols: Sustainable access to arylfurans
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Aerobic oxidative α-arylation of furans with boronic acids via Pd(ii)-catalyzed C-C bond cleavage of primary furfuryl alcohols provides sustainable access to arylfurans. This protocol opens a new avenue for the transformation of readily available furans into other useful compounds.
- Huang, Guanghao,Lu, Lin,Jiang, Huanfeng,Yin, Biaolin
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supporting information
p. 12217 - 12220
(2017/11/16)
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- Polyaniline-Induced Arylation with Arenediazonium Salts Derived from Anilines
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A catalytic amount of a reduced form of polyaniline (a redox-active π-conjugated polymer) was found to induce C?H direct arylation of (hetero)arenes with arenediazonium salts prepared from anilines with methanesulfonic acid (MeSO3H) and tert-butyl nitrite (tBuONO). The difficult part of this method is the coexistence of an oxidant and a reductant in this sequential diazotization and arylation system; diazotization requires weak oxidants such as alkyl nitrites, whereas the arylation is induced by a reductant. This was achieved by the careful control of the amount of tBuONO (1.0 equivalent) for the diazotization step, and sequential arylation using 5 mol % of the polyaniline. The reaction took place under mild conditions without any metals or strong bases at room temperature, and the amino group is a formal leaving group. The scope of the substrates demonstrates the versatility in the combination of anilines with a variety of functional groups and several (hetero)arenes. Two-directional arylation for the synthesis of an unsymmetrical 1,4-diarylated (furyl and pyrrolyl groups) benzene was achieved, using mono-Boc-protected 1,4-phenylenediamine as a substrate. This shows potential for the synthesis of more complicated oligoarene compounds.
- Hata, Dai,Moriuchi, Toshiyuki,Hirao, Toshikazu,Amaya, Toru
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supporting information
p. 7703 - 7709
(2017/06/06)
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- A co-operative effect of visible light photo-catalysis and CoFe2O4 nanoparticles for green synthesis of furans in water
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A novel approach to poly-functionalized furan synthesis is disclosed via oxidative decarboxylative [3+2] cycloaddition using co-operative catalysis by visible light and CoFe2O4 nanoparticles under ambient reaction conditions with water as a solvent. Although the reported method is efficient without catalyst in the presence of visible light (70% yield in 4 h at rt), the use of catalyst not only increases the yield (91%) but also accelerates the conversion rate (2 h at rt).
- Verma, Fooleswar,Singh, Puneet K.,Bhardiya, Smita R.,Singh, Manorama,Rai, Ankita,Rai, Vijai K.
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supporting information
p. 4937 - 4942
(2017/07/12)
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- Copper-catalyzed direct synthesis of furans and thiophenes via decarboxylative coupling of alkynyl carboxylic acids with H2O or Na2S
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2,5-Diaryl-substituted furans were synthesized from the copper-catalyzed decarboxylative coupling of aryl-substituted aryl propiolic acids in the presence of H2O. The homocoupling of alkynyl carboxylic acids provided 1,4-diaryldiynes, which then reacted with H2O to give the desired furans through cyclization. Addition of the copper catalyst was critical, and the addition of a ligand increased the yield of products in both the homocoupling and cyclization reactions. In addition, thiophenes could be obtained when the reaction was conducted in the presence of Na2S.
- Irudayanathan, Francis Mariaraj,Edwin Raja, Gabriel Charles,Lee, Sunwoo
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p. 4418 - 4425
(2015/06/08)
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- Copper(II)-Promoted, One-Pot Conversion of 1-Alkynes with Anhydrides or Primary Amines to the Respective 2,5-Disubstituted Furans or Pyrroles under Microwave Irradiation Conditions
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Furans and pyrroles are prepared from 1-alkynes by using a Cu(II)-promoted, one-pot, microwave irradiation method. Glaser coupling of 1-alkynes and cyclization of the resulting 1,3-diyne in the presence of an anhydride or a primary amine results in the formation of the respective 2,5-diaryl- or 2,5-dialkyl-substituted furans and pyrroles.
- Lee, Hyejeong,Yi, Yeonhui,Jun, Chul-Ho
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p. 3485 - 3490
(2016/01/25)
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- Successively recycle waste as catalyst: A one-pot wittig/1,4-reduction/paal-knorr sequence for modular synthesis of substituted furans
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A one-pot tandem Wittig/conjugate reduction/Paal-Knorr reaction is reported for the synthesis of di- or trisubstituted furans. This novel sequence first demonstrates the possibility of successively recycling waste from upstream steps to catalyze downstream reactions.
- Chen, Long,Du, Yi,Zeng, Xing-Ping,Shi, Tao-Da,Zhou, Feng,Zhou, Jian
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p. 1557 - 1560
(2015/03/30)
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- Gold-catalyzed formation of C-O and C-C bonds: An efficient domino reaction synthesis of functionalized furans
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An efficient gold-catalyzed domino reaction for the synthesis of furan derivatives from haloalkynes has been described. This transformation has provided a new route for the formation of C-O and C-C bonds that prepare functionalized furans.
- Guo, Pengfeng
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- Visible-light-induced Ci-S bond activation: Facile access to 1,4-diketones from β-ketosulfones
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A novel method for the synthesis of 1,4-diketones from β-ketosulfones was developed by means of a visible light-induced Ci￡S bond activation process. Symmetrical and unsymmetrical 1,4-diketones can be easily prepared in moderate to good yields. A new and efficient method for the synthesis of 1,4-diketones from β-ketosulfones was developed by means of a visible-light-induced Ci￡S bond activation process (see scheme). Symmetrical and unsymmetrical 1,4-diketones can be easily prepared in moderate to good yields.
- Xuan, Jun,Feng, Zhu-Jia,Chen, Jia-Rong,Lu, Liang-Qiu,Xiao, Wen-Jing
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supporting information
p. 3045 - 3049
(2014/03/21)
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- Oxidative coupling of terminal alkyne with α-hydroxy ketone: An expedient approach toward ynediones
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An efficient and mild copper-catalyzed one-pot approach toward ynediones has been established. A variety of ynediones were constructed directly through oxidative coupling of alkyne with α-hydroxy ketone. Oxygen-oxidizing and neutral conditions in one-pot for a wide range of substrates including natural product derivatives make this transformation highly efficient and practical. On the basis of control experiments, in situ IR measurements, and isotopic labeling experiments, a plausible mechanism involving intermediate phenylglyoxal was drawn. Applications by synthesis of various heterocycles were also investigated.
- Zhang, Zeguang,Jiang, Xuefeng
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p. 4400 - 4403
(2015/02/18)
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- A general approach to arylated furans, pyrroles, and thiophenes
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A general and practical synthetic method for aryl-substituted five-membered heterocycles has been developed. In the presence of KOH (30%), 1,4-diaryl-1,3-butadiynes undergo the cyclocondensation reaction with water, primary amines, and Na2S·9H2O in DMSO at 80 °C to afford 2,5-diarylfurans, 1,2,5-trisubstituted pyrroles, and 2,5-diarylthiophenes in good to high yields. Further studies have disclosed that aryl-substituted five-membered heterocycles can be also synthesized by a one-pot, two-step strategy from the terminal alkynes in DMSO firstly catalyzed by CuCl, and then via addition of KOH to promote the cyclocondensation of 1,3-butadiynes generated in situ.
- Zheng, Qingwei,Hua, Ruimao,Jiang, Jianhua,Zhang, Lei
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p. 8252 - 8256
(2015/03/05)
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- Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira-Glaser cyclization sequence
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2,5-Di(hetero)arylfurans are readily accessible in a pseudo five-component reaction via a Sonogashira-Glaser coupling sequence followed by a superbase-mediated (KOH/DMSO) cyclization in a consecutive one-pot fashion. Besides the straightforward synthesis of natural products and biologically active molecules all representatives are particularly interesting due to their bright blue luminescence with remarkably high quantum yields. The electronic structure of the title compounds is additionally studied with DFT computations.
- Klukas, Fabian,Grunwald, Alexander,Menschel, Franziska,Mueller, Thomas J. J.
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supporting information
p. 672 - 679
(2014/04/17)
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- A highly efficient synthesis of 2,5-disubstituted furans from enyne acetates catalyzed by lewis acid and palladium
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A highly efficient synthesis of a wide range of 2,5-disubstituted furans from enyne acetates is described. The reactions are conducted by using Lewis acid and palladium catalyst and provide symmetrical and unsymmetrical products in good to excellent yields, with broad substrate scope, including a variety of aromatic and aliphatic substituents in the 2- and 5-position of the furan ring.
- Chen, Zheng-Wang,Luo, Miao-Ting,Wen, Yue-Lu,Ye, Min,Zhou, Zhong-Gao,Liu, Liang-Xian
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supporting information
p. 2341 - 2344
(2015/08/06)
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- A sequential synthesis of substituted furans from aryl alkynes and ketones involving a cerium(IV) ammonium nitrate (CAN)-mediated oxidative cyclization
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A convenient, two-step synthesis of substituted furans from readily available aryl alkynes and ketones is reported. The furan-forming oxidative cyclization is mediated by the combination of cerium(IV) ammonium nitrate and potassium bromide and can be carried out in an open flask.
- Undeela, Sridhar,Ramchandra, Joshi P.,Menon, Rajeev S.
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p. 5667 - 5670
(2014/12/12)
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- Oxidative cross-coupling of allenyl ketones and organoboronic acids: Expeditious synthesis of highly substituted furans
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Allenyl ketones are employed as coupling partners in palladium-catalyzed oxidative cross-coupling reactions with organoboronic acids. This reaction constitutes an efficient methodology for the synthesis of highly substituted furan derivatives. Palladium-carbene migratory insertion is proposed as the key step in this transformation. Migration patterns: Allenyl ketones are employed as a coupling partner in a palladium-catalyzed oxidative cross-coupling reaction with organoboronic acids. This reaction constitutes an efficient methodology for the synthesis of highly substituted furan derivatives. Palladium-carbene migratory insertion is proposed as the key step in this transformation. BQ=1,4-benzoquinone.
- Xia, Ying,Xia, Yamu,Ge, Rui,Liu, Zhen,Xiao, Qing,Zhang, Yan,Wang, Jianbo
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supporting information
p. 3917 - 3921
(2014/05/06)
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- ZnII- and AuI-catalyzed regioselective hydrative oxidations of 3-En-1-ynes with selectfluor: Realization of 1,4-dioxo and 1,4-oxohydroxy functionalizations
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Catalytic 1,4-dioxo functionalizations of 3-en-1-ynes to (Z)- and (E)-2-en-1,4-dicarbonyl compounds are described. This regioselective difunctionalization was achieved in one-pot operation through initial alkyne hydration followed by in situ Selectfluor oxidation. The presence of pyridine alters the reaction chemoselectivity to give 4-hydroxy-2-en-1-carbonyl products instead. A cooperative action of pyridine and ZnII assists the hydrolysis of key oxonium intermediate.
- Jadhav, Appaso Mahadev,Gawade, Sagar Ashok,Vasu, Dhananjayan,Dateer, Ramesh B.,Liu, Rai-Shung
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p. 1813 - 1817
(2014/03/21)
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- The rearrangement of tert -butylperoxides for the construction of polysubstituted furans
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The Bronsted acid catalyzed rearrangement of tert-butyl peroxides provides a new strategy to construct 2,3-disubstituted furans via 1,2-aryl migration. In addition, tert-butyl peroxides could also be transformed into 2,3,5-trisubstituted or 2,5-disubstituted furans through a sequence of base-catalyzed Kornblum-DelaMare rearrangements and acid-promoted Paal-Knorr reactions.
- Zheng, Xiaojian,Lu, Shenglin,Li, Zhiping
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supporting information
p. 5432 - 5435
(2013/11/19)
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- Copper-impregnated magnetite as a heterogeneous catalyst for the homocoupling of terminal alkynes
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Copper-impregnated magnetite is a versatile heterogeneous catalytic system for the synthesis of 1,3-diynes by the homocoupling of terminal alkynes. This catalyst does not require the use of pressurized oxygen as the oxidant and it does not need a solvent or harsh conditions to give the expected products. Moreover, the catalyst can be removed from the reaction medium simply by using a magnet. The reaction occurs at the lowest copper loading reported for any heterogeneous catalyst.
- Perez, Juana M.,Cano, Rafael,Yus, Miguel,Ramon, Diego J.
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p. 1373 - 1379
(2013/07/05)
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- Synthesis of polysubstituted furans via copper-mediated annulation of alkyl ketones with α,β-unsaturated carboxylic acids
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A novel copper-mediated annulation of alkyl ketones with α,β-unsaturated carboxylic acids has been accomplished. This reaction provides a facile and regio-defined method for the synthesis of 2,3,5-trisubstituted furans from simple chemical reagents.
- Yang, Yuzhu,Yao, Jinzhong,Zhang, Yuhong
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supporting information
p. 3206 - 3209
(2013/07/26)
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- Synthesis, crystal structure and binding properties of a new fluorescent molecular clip based on 2,5-diphenylfuran
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A new fluorescent molecular clip derived from 2,5-diphenyl-furan with two benzo[d]-thiazole-2-thio-units as side walls has been synthesised and its structure and conformation confirmed by an X-ray structure. Fluorescence spectroscopic studies show that it can selectively bind Fe3+.
- Sheng-Li, Hu,Cai-Hua, Xu,Shu-Shu, Zhang,Wen-Bing, Sun,Qing, Gao
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p. 210 - 212
(2013/07/27)
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- Organic synthesis in deep eutectic solvents: Paal-Knorr reactions
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Deep eutectic solvents (the combination of either urea or glycerol with choline chloride) are effective solvents/catalysts for Paal-Knorr reactions to form pyrroles of furans. The reaction conditions are quite mild and do not require the addition of an additional Bronsted or Lewis acid catalyst. Given the inexpensive, non-toxic, and recyclable nature of the DES, these reaction conditions are simple and highly environmentally friendly.
- Handy, Scott,Lavender, Kevin
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supporting information
p. 4377 - 4379
(2013/07/26)
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- Oxidative ring opening of 1,3-diarylbenzo[c]heterocycles using m-CPBA: Preparation of 1,2-diaroylbenzenes
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An unprecedented oxidative cleavage of benzo[c]heterocycles using m-CPBA is reported. The reaction of 1,3-diaryl benzo[c]heterocycles with m-CPBA (meta-chloroperoxybenzoic acid) at room temperature for 5 min led to the formation of 1,2-diaroylbenzenes in good to excellent yields.
- Nandakumar, Meganathan,Sivasakthikumaran, Ramakrishnan,Mohanakrishnan, Arasambattu K.
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supporting information; experimental part
p. 3647 - 3657
(2012/07/27)
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- Mono- and biscouplings using triarylbismuths for the atom-efficient arylations of functionalized furans under palladium catalysis
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Palladium-catalyzed cross-coupling reactions of functionalized bromofurans with triarylbismuths have been described for the atom-economic synthesis of functionalized arylfuran systems. The coupling reactions using triarylbismuths with various 2-bromofurans and 2,5-dibromofuran underwent smoothly to afford the corresponding 2-arylfurans and 2,5-diarylfurans in high yields in a short reaction time (one hour). Georg Thieme Verlag Stuttgart · New York.
- Rao, Maddali L. N.,Awasthi, Dheeraj K.,Talode, Jalindar B.
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supporting information; experimental part
p. 1907 - 1912
(2012/09/22)
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- Woollins reagent: A chemoselective reducing agent for 1,4-enediones and 1,4-ynediones to saturated 1,4-diones
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Woollins reagent was found to act as a highly chemoselective reagent for the reduction of a wide range of 1,4-enediones and 1,4-ynediones in methanol to afford the corresponding saturated 1,4-diketones in good yields under mild reaction conditions.
- Mandal, Madhumita,Chatterjee, Sourav,Jaisankar, Parasuraman
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supporting information
p. 2615 - 2618,4
(2012/12/12)
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- Copper(I)-catalyzed synthesis of 2,5-disubstituted furans and thiophenes from haloalkynes or 1,3-diynes
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A regioselective synthesis of 2,5-disubstituted furans using copper(I) catalyst from haloalkynes in a one-pot procedure has been reported. This chemistry proceeds through the hydration reaction of 1,3-diynes, which can be readily prepared from the coupling reaction of haloalkynes in the presence of CuI. The procedure also can be used for the facile synthesis of 2,5-disubstituted thiophenes.
- Jiang, Huanfeng,Zeng, Wei,Li, Yibiao,Wu, Wanqing,Huang, Liangbing,Fu, Wei
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experimental part
p. 5179 - 5183
(2012/07/03)
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- Ru- and Pd-catalysed synthesis of 2-arylfurans by one-flask heck arylation/oxidation
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2,5-Disubstituted furans were synthesized by one-flask Heck arylation/oxidation sequences. The starting materials are 2-substituted 2,3-dihydrofurans, conveniently available by RCM/isomerization sequences, and arenediazonium salts. These react in ligand-free Heck reactions to afford 2,5-disubstituted 2,5-dihydrofurans, which are oxidized to the corresponding furans without isolation or intermediate workup. The oxidation is conveniently achieved with chloranil or DDQ, depending on the substrate.
- Schmidt, Bernd,Geissler, Diana
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p. 4814 - 4822
(2011/10/09)
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- Ionic liquid as catalyst and reaction medium: A Simple and Efficient Procedure for Paal-Knorr furan synthesis
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The ionic liquid 1-butyl-3-methyl-imidazolium hydrogen sulfate, [bmim]HSO4, efficiently catalyzes Paal-Knorr furan synthesis without any organic solvent. A wide range of aliphatic and aromatic 1,4-diketones easily undergo condensations to form furan derivatives, providing a general and convenient procedure. The Paal-Knorr reaction of ester-substituted 1,4-diketones is first reported. The ionic liquid can be recovered and reused for subsequent runs without any appreciable loss of efficiency.
- Wang, Gangqiang,Guan, Zhi,Tang, Rongchang,He, Yanhong
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experimental part
p. 370 - 377
(2010/04/04)
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- Access to 2,5-diamidopyrroles and 2,5-diamidofurans by Au(I)-catalyzed double hydroamination or hydration of 1,3-diynes
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(Figure presented) A Au(I)-catalyzed hydroamination or hydration of 1,3-diynes to access 2,5-diamidopyrroles and 2,5-diamidofurans has been developed. This method can also be expanded to 2,5-disubstituted furans and 1,2,5-trisubstituted pyrroles including the formation of deuterated heterocycles and 18O-labeled furans.
- Kramer, Soren,Madsen, Julie L. H.,Rottlaender, Mario,Skrydstrup, Troels
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supporting information; experimental part
p. 2758 - 2761
(2010/08/22)
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- New synthesis of furans: The rhodium-catalysed carbonylative addition of arylboronic acids to propargylic alcohols/cyclisation sequence
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The rhodium-catalysed carbonylative addition of arylboronic acids to propargylic alcohols yields gamma-hydroxy enones that are readily cyclised through a dehydration step to the corresponding furan analogues. The transformation was improved thanks to the screening of the reaction conditions and consequent improvements were obtained from the use of dicarbonylrhodium iodide [Rh(CO)2I]2 as catalyst precursor. The generalisation of the reaction was then further investigated by employing variously substituted arylboronic acids and propargylic alcohols.
- Dheur, Julien,Sauthier, Mathieu,Castanet, Yves,Mortreuxa, Andre
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experimental part
p. 557 - 561
(2010/06/13)
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- Iridium-catalyzed addition of acid chlorides to terminal alkynes
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(Chemical Equation Presented) An iridium N-heterocyclic carbene (NHC) complex, IrCl(cod)(IPr), successfully catalyzed an addition of common aromatic acid chlorides to terminal alkynes to afford (Z)-β-chloro-α,β- unsaturated ketones regio- and stereoselectively. When the NHC ligand (IPr) was changed to a phosphine (RuPhos), the addition occurred with decarbonylation to give the corresponding (Z)-vinyl chlorides. Furthermore, the former reaction using IrCl(cod)(IPr) can be applied to the catalytic synthesis of 2,5-disubstituted furans.
- Iwai, Tomohiro,Fujihara, Tetsuaki,Terao, Jun,Tsuji, Yasushi
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supporting information; experimental part
p. 6668 - 6669
(2009/10/30)
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- Syntheses of substituted furans and pyrroles by platinum-catalyzed cyclizations of propargylic oxiranes and aziridines in aqueous media
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The reactions of propargylic oxiranes and aziridines with a platinum catalyst in aqueous media are described. Furans having a variety of substituents were conveniently synthesized by the platinum-catalyzed reaction of propargylic oxiranes. The reaction in the presence of N-iodosuccinimide afforded the 3-iodo-substituted furan, which was further functionalized to tetrasubstituted furans with high efficiency. Propargylic aziridines were also reacted with the platinum catalyst to produce the corresponding substituted pyrroles in good yields. Georg Thieme Verlag Stuttgart.
- Yoshida, Masahiro,Al-Amin, Mohammad,Shishido, Kozo
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experimental part
p. 2454 - 2466
(2010/01/16)
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- Cationic gold(I)-mediated intramolecular cyclization of 3-alkyne-1,2-diols and 1-amino-3-alkyn-2-ols: A practical route to furans and pyrroles
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The intramolecular cyclizations of the 3-alkyne-1,2-diols and the 1-amlno-3-alkyn-2-ols with a low catalyst loading (0.05-0.5 mol %) of (Ph 3P)AuCl - AgNTf2 or (Ph3P)AuCl-AgOTf proceeded at room temperature to provide a variety of substituted furans and pyrroles In excellent yields (85-98% yields). This method Is also fully applicable to the conversion of several dozen grams of the substrate using only 0.05 mol % each of the Au and Ag catalysts.
- Egi, Masahiro,Azechi, Kenji,Akai, Shuji
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supporting information; experimental part
p. 5002 - 5005
(2009/12/26)
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- Sequential synthesis of furans from alkynes: Successive ruthenium(II)- and copper(II)-catalyzed processes
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(Chemical Equation Presented) Step in time: 2,5-Disubstituted furans can be prepared from terminal alkynes in one pot using two successive catalytic reactions (see scheme; p-TSA=para-toluene-sulfonic acid). First, a 1,3-dienyl alkyl ether is produced by t
- Zhang, Min,Jiang, Huan-Feng,Neumann, Helfried,Beller, Matthias,Dixneuf, Pierre H.
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supporting information; scheme or table
p. 1681 - 1684
(2009/06/30)
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- Synthesis of 2-aryl- and 2,5-diarylfurans and thiophenes by Suzuki-Miyaura reactions using potassium trifluoroborate salts and heteroaryltellurides
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The Suzuki-Miyaura cross-coupling reaction of 2-(butyltellanyl) or 2,5-bis-(butyltellanyl)furans and thiophenes with potassium aryltrifluoroborate salts catalyzed by palladium afforded 2-aryl- or 2,5-diaryl-furans and thiophenes in moderate to good yields.
- Botteselle, Giancarlo V.,Hough, Thomas L. S.,Venturoso, Raphael C.,Cella, Rodrigo,Vieira, Adriano S.,Stefani, Helio A.
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experimental part
p. 870 - 873
(2009/04/11)
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- A new facile approach to the synthesis of 3-methylthio-substituted furans, pyrroles, thiophenes, and related derivatives
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(Chemical Equation Presented) 2-(Methylthio)-1,4-diaryl-2-butene-1,4-dione (3) are prepared from readily available aryl methyl ketones in the presence of copper(II) oxide, iodine, and dimethyl sulfoxide. The success of the cross-coupling reaction of 4-chloroacetophenone with 2-acetylthiophene confirms a proposed self-sorting tandem reaction mechanism. Both Z- and E-isomers of compound 3 are readily converted into the corresponding 3-methylthio 2,5-diaryl furan 7 in good yield through a domino process involving the reduction of the double bond followed by the Paal-Knorr furan synthesis. Meanwhile, 4-bromo-3-methylthio 2,5-diaryl furan 10 is obtained either by the treatment of furan 7 with molecular bromine or by the treatment of diketone 3 with 30% hydrogen bromide in acetic acid solution in one pot. Removal of the methylthio group is accomplished by the treatment of 7 with Raney Ni in ethanol, which affords the diaryl-substituted furan 11 in excellent isolated yield. Selective reduction of the double bond of compound 3 leads to the formation of the saturated 1,4-diketone 13, which is easily converted to the corresponding 3-methylthio-2,5-diaryl-substituted pyrrole 14 and thiophene 15 via the Paal-Knorr cyclization reaction.
- Yin, Guodong,Wang, Zihua,Chen, Aihua,Gao, Meng,Wu, Anxin,Pan, Yuanjiang
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p. 3377 - 3383
(2008/09/21)
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