- A tandem palladium-catalyzed Heck-lactonization through the reaction of ortho-iodophenols with β-substituted acrylates: synthesis of 4,6-substituted coumarins
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Coumarins were obtained in one pot through a palladium-catalyzed Heck-lactonization reaction involving ortho-iodophenols and methyl crotonate or a Z-enoate derived from d-mannitol. These reactions were investigated under different conditions and palladium sources. In the more interesting cases, coumarins were prepared in water, using triethylamine as base and 1 mol % of PdCl2 as catalyst.
- Fernandes, Talita de A.,Carvalho, Rita de C.C.,Gon?alves, Tatiana M.D.,da Silva, Alcides J.M.,Costa, Paulo R.R.
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- Immobilized ionic liquid on the zeolite: its characterization and catalytic activity in the synthesis of coumarins via Pechmann reaction
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In this work, in the first step, the 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride ([MTMSPIm]Cl) is immobilized on HY and NaY zeolites as an acidic catalyst. The synthesized catalysts were well characterized by different methods such as FTIR, TGA, XRD, BET, SEM, EDX and ICP. The characterizations of catalysts indeed show the ionic liquid supported on amine-functionalized zeolites. Also, the result shows the micro-/mesoporous structure for catalysts which have been emerged as an important class of catalytic materials. The micro-/mesocatalyst ([MTMSPIm]Cl@zeolite) was used as an acidic catalyst to synthesize coumarins via Pechmann reaction in solvent-free condition. The effect of different factors such as catalyst amount, solvent and time was investigated. Finally, catalyst can be easily separated and reused for the next reactions at least for five runs without any significant changes in yield and structure of the catalyst. Comparison of modified zeolite with [MTMSPIm]Cl shows higher yield and selectivity and mild condition related to other works.
- Zendehdel, Mojgan,Khaghaninejad, Soheila,Tavakoli, Fatemeh,Ganji, Shiva
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- Iridium-catalyzed enantioselective direct vinylogous allylic alkylation of coumarins
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The first iridium-catalyzed enantioselective vinylogous allylic alkylation of coumarins is presented. Using easily accessible linear allylic carbonates as the allylic electrophile, this reaction installs unfunctionalized allyl groups at the γ-position of
- Sarkar, Rahul,Mitra, Sankash,Mukherjee, Santanu
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- Coumarin derivatives solvent-free synthesis under microwave irradiation over heterogeneous solid catalysts
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A suitable methodology of synthesis of coumarin derivatives by Pechmann reaction over heterogeneous solid acid catalysts in a free solvent media under microwave irradiation is described. Resorcinol, phenol and ethyl acetoacetate were selected as model reactants in the Pechmann condensation. The catalytic activity of several materials—Amberlyst-15, zeolite β and sulfonic acid functionalized hybrid silica—in solvent-free microwave-assisted synthesis of the corresponding coumarin derivatives has been investigated in detail. 7-Hydroxy-4-methylcoumarin and 4-methylcoumarin were obtained in 97% and 43% yields, respectively, over Amberlyst-15. This was the most active catalyst in the Pechmann reaction under studied conditions.
- Bouasla, Souad,Amaro-Gahete, Juan,Esquivel, Dolores,López, M Isabel,Jiménez-Sanchidrián, César,Teguiche, Mabrouk,Romero-Salguero, Francisco J
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- Shape-, size-, and functional group-selective binding of small organic guests in a paramagnetic coordination cage
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The host-guest chemistry of the octanuclear cubic coordination cage [Co8L12]16+ (where L is a bridging ligand containing two chelating pyrazolyl-pyridine units connected to a central naphthalene-1,5-diyl spacer via methylene "hinges") has been investigated in detail by 1H NMR spectroscopy. The cage encloses a cavity of volume of ca. 400 A3, which is accessible through 4 A diameter portals in the centers of the cube faces. The paramagnetism of the cage eliminates overlap of NMR signals by dispersing them over a range of ca. 200 ppm, making changes of specific signals easy to observe, and also results in large complexation-induced shifts of bound guests. The cage, in CD3CN solution, acts as a remarkably size-and shape-selective host for small organic guests such as coumarin (K = 78 M-1) and other bicyclic molecules of comparable size and shape such as isoquinoline-N-oxide (K = 2100 M-1). Binding arises from two independent recognition elements, which have been separately quantified. These are (i) a polar component arising from interaction of the H-bond accepting O atom of the guest with a convergent group of CH protons inside the cavity that lie close to a fac tris-chelate metal center and are therefore in a region of high electrostatic potential; and (ii) an additional component arising from the second aromatic ring (aromatic/van der Waals interactions with the interior surface of the cage and/or solvophobic interactions). The strength of the first component varies linearly with the H-bond-accepting ability of the guest; the second component is fixed at approximately 10 kJ mol-1. We have also used 1H-1H exchange spectroscopy (EXSY) experiments to analyze semiquantitatively two distinct dynamic processes, viz. movement of the guest into and out of the cavity and tumbling of the guest inside the host cavity. Depending on the size of the guest and the position of substituents, the rates of these processes can vary substantially, and the rates of processes that afford observable cross-peaks in EXSY spectra (e.g., between free and bound guest in some cases; between different conformers of a specific host·guest complex in others) can be narrowed down to a specific time window. Overall, the paramagnetism of the host cage has allowed an exceptionally detailed analysis of the kinetics and thermodynamics of its host-guest behavior.
- Turega, Simon,Whitehead, Martina,Hall, Benjamin R.,Meijer, Anthony J. H. M.,Hunter, Christopher A.,Ward, Michael D.
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- Intramolecular Cyclization of ortho-Iodophenyl 3-Butenoate to 4-Methylcoumarin: Catalysis by Palladium Complexes
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A new palladium-catalyzed synthesis of 4-alkylcoumarins is reported, based on intramolecular arylation of the 3-alkenoic chain of an ortho-iodophenyl ester. - Key Words: coumarin, palladium catalysis, cyclization.
- Catellani, Marta,Chiusoli, Gian Paolo,Fagnola, Maria Chiara,Solari, Giovanna
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- B(C6F5)3-catalyzed synthesis of coumarins via Pechmann condensation under solvent-free conditions
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Tris(pentafluorophenyl)borane [B(C6F5)3] catalyzed simple, efficient and environmentally benign protocol has been developed for the Pechmann condensation using variety of phenols and β-ketoesters under solvent-free conditions to afford coumarin derivatives. The present protocol displayed significant advantages such as low catalyst loading, short reaction time, mild reaction conditions, low toxicity, easy work-up, high yields, and compatibility with other functional groups. In addition, it is a convenient, clean, and fast alternative approach for synthesizing variety of coumarin derivatives. Moreover, the applicability of this method towards large-scale synthesis demonstrated its suitability for the industrial application. Graphic abstract: [Figure not available: see fulltext.]
- Prajapti, Santosh Kumar,Rao, S. Prakash
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p. 469 - 473
(2021/03/26)
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- Functionalizing HY zeolite with sulfonic acid, a micro-meso structure reusable catalyst for organic transformations
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A new class of sulfonic acid functionalized HY zeolite (HY-N-SA) catalyst has been prepared and characterized by some method such as XRD, FT-IR, FESEM, TEM, TGA, NH3-TPD and N2 physisorption. The result shows the micro-meso structure for catalyst without ordering in the mesophase. Then, the HY-N-SA micro-meso structure was used as an acidic catalyst to synthesize of coumarins via Pechmann reaction and facile transformation of amines to formamides under solvent-free condition. To consider the effect of acidity and kind and size of porous on the catalyst activity, this catalyst was compared with NaY-N-SA and MCM-N-SA and pure porous material (NaY and MCM-41). The significant advantages of HY-N-SA with respect to other catalysts are short reaction times, high yields, pure products, mild conditions and easy work-up. In addition, we report an original and environmentally friendly solvent-free procedure which reusability of catalyst makes this method nearly green and environmentally friendly.
- Tavakoli, Fatemeh,Zendehdel, Mojgan
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- Nickel-Catalyzed Hydrodeoxygenation of Aryl Sulfamates with Alcohols as Mild Reducing Agents
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The nickel-catalyzed hydrodeoxygenation of aryl sulfamates has been developed with alcohols as mild reductants. A variety of functional groups and heterocycles were tolerated in this reaction system to give the desired products in high yields. In addition, the gram-scale process and stepwise cine-substitution were also achieved with high efficiency.
- Matsuo, Kasumi,Kuriyama, Masami,Yamamoto, Kosuke,Demizu, Yosuke,Nishida, Koyo,Onomura, Osamu
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p. 4449 - 4460
(2021/08/25)
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- Coumarins by Direct Annulation: β-Borylacrylates as Ambiphilic C3-Synthons
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Modular β-borylacrylates have been validated as programmable, ambiphilic C3-synthons in the cascade annulation of 2-halo-phenol derivatives to generate structurally and electronically diverse coumarins. Key to this [3+3] disconnection is the BPin unit which serves a dual purpose as both a traceless linker for C(sp2)–C(sp2) coupling, and as a chromophore extension to enable inversion of the alkene geometry via selective energy transfer catalysis. Mild isomerisation is a pre-condition to access 3-substituted coumarins and provides a handle for divergence. The method is showcased in the synthesis of representative natural products that contain this venerable chemotype. Facile entry into π-expanded estrone derivatives modified at the A-ring is disclosed to demonstrate the potential of the method in bioassay development or in drug repurposing.
- Wienhold, Max,Molloy, John J.,Daniliuc, Constantin G.,Gilmour, Ryan
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supporting information
p. 685 - 689
(2020/11/30)
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- Visible-light promoted oxidative cyclization of cinnamic acid derivatives using xanthone as the photocatalyst
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We have developed an efficient photocatalytic synthesis of coumarin derivativesviaa tandem double bond isomerization/oxidative cyclization of cinnamic acids. Inexpensive and stable xanthone was used as the photocatalyst, and readily available Selectfluor was used as the oxidant. This method tolerates a wide range of functional groups and offers excellent chemical yields in general. Besides, the photocatalytic oxidative cyclization of cinnamic acid esters gives dimerized lignan-type products.
- Zhao, Bin,Xu, Bo
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supporting information
p. 568 - 573
(2021/02/06)
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- Boron-enabled geometric isomerization of alkenes via selective energy-transfer catalysis
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Isomerization-based strategies to enable the stereodivergent construction of complex polyenes from geometrically defined alkene linchpins remain conspicuously underdeveloped. Mitigating the thermodynamic constraints inherent to isomerization is further frustrated by the considerations of atom efficiency in idealized low–molecular weight precursors. In this work, we report a general ambiphilic C3 scaffold that can be isomerized and bidirectionally extended. Predicated on highly efficient triplet energy transfer, the selective isomerization of b-borylacrylates is contingent on the participation of the boron p orbital in the substrate chromophore. Rotation of the C(sp2)–B bond by 90° in the product renders re-excitation inefficient and endows directionality. This subtle stereoelectronic gating mechanism enables the stereocontrolled syntheses of well-defined retinoic acid derivatives.
- Molloy, John J.,Sch?fer, Michael,Wienhold, Max,Morack, Tobias,Daniliuc, Constantin G.,Gilmour, Ryan
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p. 302 - 306
(2020/08/11)
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- Catalytic Activity of a Zr MOF Containing POCOP-Pd Pincer Complexes
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A metal-organic framework assembled from POCOP-Pd pincer complex metallolinkers (1-PdBF4, Zr6O4(OH)4(L-PdMeCN)3(BF4)3, L = (2,6-(OPAr2)2C6H3, Ar = p-C6H4CO2-) has been generated via postsynthetic oxidative I-/BF4- ligand exchange with NOBF4. 1-PdBF4 catalyzes a range of organic transformations, including transfer hydrogenation of unsaturated organic substrates, terminal alkyne hydration, and intramolecular hydroarylation of alkynes. The homogeneous analogue, tBu4POCOP-PdBF4, shows poor catalytic activity for transfer hydrogenation and alkyne hydration and decomposes under the catalytic reaction conditions. Solubility limitations and catalyst deactivation pathways observed for the homogeneous pincer complex propound the advantages of using porous solid supports to immobilize organometallic species.
- Kassie, Abebu A.,Wade, Casey R.
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p. 2214 - 2221
(2020/07/06)
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- New chromophores based on 2-(4-vinylchromen-2-ylidene)malononitrile and 2-(2-vinylchromen-4-ylidene)malononitrile
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New derivatives of 2-(4-vinylchromen-2-ylidene)malononitrile and 2-(2-vinylchromen-4-ylidene)malononitrile were synthesized using the Knoevenagel reaction of 2-(4-methyl-chromen-2-ylidene)malononitrile and 2-(2-methylchromen-4-ylidene)malononitrile, respectively, with the participation of [1-(2-n-butoxyethyl)-2,2,4,7-tetramethyl-1,2,3,4-tetrahydroquinolin-6-yl)]-carbaldehyde. First hyperpolarizability (β) was calculated for the obtained compounds using the M05-2X functional and 6-31+G (d) basis. Optical properties and solvatochromism in solvents of different polarity (toluene, 1,4-dioxane, chlorobenzene, dichloromethane, DMF, and ethanol) were also investigated.
- Levchenko,Chudov,Demin, D. Yu.,Adamov,Zinoviev,Lyssenko,Shokurov,Shmelin,Grebennikov
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p. 1883 - 1888
(2019/10/22)
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- Sequential Energy Transfer Catalysis: A Cascade Synthesis of Angularly-Fused Dihydrocoumarins
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An operationally simple one-pot protocol has been developed to enable the conversion of diversely substituted cinnamic acid derivatives into angularly-fused dihydrocoumarins (up to 94%). Inspired by coumarin biosynthesis, this reaction cascade harnesses photochemical E → Z alkene isomerization enabled by energy transfer catalysis using inexpensive thioxanthen-9-one (TX) under irradiation at 402 nm. Subsequent lactonization generates the heterocyclic core prior to a second photosensitization event to induce a [2 + 2] cycloaddition, again mediated by TX. The tetracyclic products are generated efficiently, and proof of the structure was established by X-ray crystallography. Mechanistic investigations, including structural probes and NMR reaction monitoring, support the postulated order of events. The study underscores the synthetic value of inexpensive small-molecule organic photocatalysts in the generation of structural complexity via sequential ?€-bond activation.
- Nevesely, Tomá?,Daniliuc, Constantin G.,Gilmour, Ryan
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supporting information
p. 9724 - 9728
(2019/11/29)
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- Synthesis of new 2-(4-vinyl-2H-chromen-2-ylidene)malononitrile-based chromophores
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An approach towards new 2-(4-vinyl-2H-chromen-2-ylidene)malononitriles-derived chromophores was developed. The optical, solvatochromic, and electrochemical properties of the synthesized compounds were studied. The first hyperpolarizability (β) was calculated using M06-2x functional with 6–31+G* basis set. The synthesized compounds absorb at a wide spectral range, from 350 to 770 nm. Divinylthiophene-bridged compound showing the narrowest band gap (1.78 eV), strong solvatochromic effect, and the highest first hyperpolarizability value (β = 47805) was found to be the most promising of the synthesized chromophores.
- Levchenko,Demin, D. Yu.,Chicheva,Chudov,Zinov’ev,Lyssenko,Fakhrutdinov,Adamov,Shmelin,Grebennikov
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p. 1691 - 1701
(2019/10/19)
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- Synthes?s and character?zat?on of new tr?azole and coumar?n-derived heterocycl?c compounds part I
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Synthesis of ethyl ester of acetic acid containing 5-oxo-[1,2,4] triazole ring (2) was achieved by the condensation of 3-substituted-4-amino-1H-1,2,4-triazol-5(4H)-one (1) with ethyl bromoacetate in basic medium. Compound 2, was then further reacted with hydrazine hydrate to form acid hydrazide, which is 2-(4-amino-3-substituted-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl)acetohydrazide (3). Compound 3 was later treated with three different diverse coumarin aldehydes (6, 12, 18) resulted in the formation of arylidene hydrazides as cis–trans conformers (7, 8, 13, 14, 19, 20). In conclusion, we synthesized 1,2,4-triazole Schiff bases derived from the condensation of 3-substituted-4-amino-1,2,4-triazole-5-on and formylhydroxy-4-methylcoumarin derivatives, which have been characterized by, spectroscopic measurements (IR, 1H-NMR, 13C-NMR and elemental analysis).
- Gümrük?üo?lu, Nurhan,Imran, Muhammad,Iqbal, Inam
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p. 1097 - 1106
(2020/01/09)
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- Practical, Large-Scale Preparation of Benzoxepines and Coumarins through Rhodium(III)-Catalyzed C-H Activation/Annulation Reactions
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Herein we disclose the assembly of benzoxepines and coumarins from 2-alkenylphenol precursors using [Cp*RhCl2]2 as the precatalyst and alkynes or carbon monoxide as reacting partners. The preparation of benzoxepines and coumarins can be scaled up to 33 mmol using low catalyst loadings.
- Gulías, Moisés,Marcos-Atanes, Daniel,Mascare?as, José L.,Font, Marc
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supporting information
p. 1669 - 1673
(2019/09/04)
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- Site-selective C-H bond carbonylation with CO2 and cobalt-catalysis
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Utilization of anthropogenic greenhouse gas CO2 for catalytic C-C bond formation via conversion to essentially valuable C1 synthons like CO is very challenging. The requirement of an efficient catalyst that has the ability to convert CO2 into CO and activate inert C-H bonds is the bottleneck. We herein demonstrate a tandem approach accomplished in a two-chamber system for efficient fluoride-mediated generation of CO from CO2 using disilane as a deoxygenating reagent and utilization of the in situ-produced CO gas for C-H bond carbonylation using earth-abundant cobalt catalysts. The ease of handling CO2 gas at atmospheric pressure allows us to prepare 13C labelled compounds which are otherwise difficult to achieve. The procedure developed makes it possible to utilize CO2 as a CO source, which can be widely applied as a C1 synthon that can be incorporated between C-H and N-H bonds of aromatic, hetero-aromatic and aliphatic carboxamides for the synthesis of various cyclic imides including spirocycles in a site-selective fashion. The late-stage derivatization of a well-known angiotensin receptor blocker (ARB), Telmisartan, and a well-known drug for very low-density lipoproteins (VLDLs), Gemfibrozil, is demonstrated. Further, to showcase the generality of the reaction, various pharmacologically important and privileged scaffolds like xanthone, coumarin and isatin have been synthesized with CO2 under atmospheric pressure.
- Barsu, Nagaraju,Kalsi, Deepti,Sundararaju, Basker
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p. 5963 - 5969
(2018/11/24)
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- Preparation of a novel, efficient, and recyclable magnetic catalyst, γ-Fe2O3@HAp-Ag nanoparticles, and a solvent- and halogen-free protocol for the synthesis of coumarin derivatives
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In this protocol, Ag supported on the hydroxyapatite-core–shell magnetic γ-Fe2O3nanoparticles (γ-Fe2O3@HAp-Ag NPs) as a novel, efficient, and magnetically recyclable catalyst is synthesized, and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The use of the catalyst is described in the synthesis of coumarin derivatives by the Pechmann condensation of various phenols with β-ketoesters under solvent- and halogen-free conditions at 80?°C. This novel and inexpensive method offers advantages, such as recyclability simple experimental protocol, short reaction time, minimal work-up procedure, and excellent yields of products, together with desirable, eco-friendly, green aspects by avoiding toxic elements and solvents, and ease of recovery from the reaction mixture using an external magnet.
- Abbasi, Zahra,Rezayati, Sobhan,Bagheri, Maryam,Hajinasiri, Rahimeh
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- A green and convenient approach for the one-pot solvent-free synthesis of coumarins and β-amino carbonyl compounds using Lewis acid grafted sulfonated carbon@titania composite
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Abstract: This paper reports an efficient protocol for the synthesis of coumarins via Pechmann reaction, and β-amino carbonyl compounds via aza-Michael reaction using catalytic amount of solid Lewis acid catalyst, C@TiO2–SO3–SbCl2. Six different catalysts were prepared by covalent immobilization of homogeneous Lewis acids onto sulfonated carbon@titania composite derived from amorphous carbon and nano-titania. Among various catalysts tested, C@TiO2–SO3–SbCl2 showed superior catalytic activity. The catalyst could be recycled without significant loss of its catalytic activity and demonstrated versatile catalysis for a wide range of substrates. Graphical abstract: [Figure not available: see fulltext.]
- Kour, Manmeet,Paul, Satya
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p. 327 - 337
(2017/02/10)
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- Synthesis of a NbO Type Homochiral Cu(II) Metal-Organic Framework: Ferroelectric Behavior and Heterogeneous Catalysis of Three-Component Coupling and Pechmann Reactions
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A chiral tetracarboxylic acid ligand, H4L, incorporating the (S)-(+)-2-methylpiperazine moiety in its middle, solvothermally forms a homochiral Cu(II) framework, {[Cu2(L)(H2O)2]·(4DMF)(4H2O)}n (LCu). It forms a non-interpenetrated structure consisting of [Cu2(COO)4] paddle-wheel secondary bonding units (SBUs) with NbO topology. Interestingly, the framework LCu exhibits excellent ferroelectric properties. It shows a remnant polarization (Pr) of ~3.5 μC cm-2 and a coercive field (Ec) of ~12 kV cm-1 with a distinct electric hysteresis loop. Dielectric studies of LCu reveal almost frequency-independent behavior with a dielectric constant (?r) of ~42 and a low dielectric loss (tan δ) of ~0.04 up to 106 Hz, for potential use in high-frequency applications. In addition, activated framework LCu′ having uncoordinated metal sites acts as an efficient heterogeneous catalyst in the three-component coupling of amines, aldehydes, and alkynes, as well as in Pechmann reactions of phenols with β-ketoesters.
- Gupta, Anoop K.,De, Dinesh,Katoch, Rajesh,Garg, Ashish,Bharadwaj, Parimal K.
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supporting information
p. 4697 - 4705
(2017/04/26)
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- Meglumine sulfate catalyzed solvent-free one-pot synthesis of coumarins under microwave and thermal conditions
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A convenient method has been developed for the Pechmann reaction of phenols and β-keto esters catalyzed by meglumine sulfate. Solvent-free conditions, inexpensive catalyst, short reaction times, high yield, and ease of purification of the products are the advantages of this protocol. This novel catalytic system is expected to contribute to the development of more benign Pechmann condensation reactions of phenols with β-keto esters.
- Moradi, Leila,Rabiei, Khadijeh,Belali, Fateme
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supporting information
p. 1283 - 1291
(2016/08/16)
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- Magnetic nanoparticles functionalized ethane sulfonic acid (MNESA): as an efficient catalyst in the synthesis of coumarin derivatives using Pechmann condensation under mild condition
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This paper reports an efficient heterogeneous catalyst based on sulfonic acid functionalization of magnetic nanoparticles. This new catalyst was prepared using the reaction between magnetic nanoparticles and sodium 2-bromoethane-1-sulfonate. Magnetic nanoparticles functionalized ethane sulfonic acid (MNESA) was found as efficient catalyst for the synthesis of coumarin derivatives using Pechmann condensation under mild condition. This reaction was catalyzed by MNESA under solvent-free condition at 90?°C, to give the corresponding products in excellent yields. The catalyst is easily separated from the reaction condition and can be reused for several times with consistence in the activity.
- Samadizadeh, Marjaneh,Nouri, Saeed,Kiani Moghadam, Faeze
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p. 6089 - 6103
(2016/06/01)
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- One-pot synthesis of coumarine derivatives using butylenebispyridinium hydrogen sulfate as novel ionic liquid catalyst
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Pechmann condensation reaction of 3-hydroxyphenol and ethyl acetoacetate in the presence of 1,1′‐butylenebispyridinium hydrogen sulfate as an efficient, green, and recyclable catalyst produces 7-hydroxy-4-methylcoumarin in good yield under solvent-free conditions at room temperature. This catalyst has advantages such as the following: good to excellent yields, short reaction times, simplicity in operation, and easy workup procedure.
- Rezayati, Sobhan,Sheikholeslami-Farahani, Fatemeh,Rostami-Charati, Faramarz,Abad, Saeid Afshari Sharif
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p. 4097 - 4107
(2016/07/06)
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- One Photocatalyst, n Activation Modes Strategy for Cascade Catalysis: Emulating Coumarin Biosynthesis with (-)-Riboflavin
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Generating molecular complexity using a single catalyst, where the requisite activation modes are sequentially exploited as the reaction proceeds, is an attractive guiding principle in synthesis. This requires that each substrate transposition exposes a catalyst activation mode (AM) to which all preceding or future intermediates are resistant. While this concept is exemplified by MacMillan's beautiful merger of enamine and iminium ion activation, examples in other fields of contemporary catalysis remain elusive. Herein, we extend this tactic to organic photochemistry. By harnessing the two discrete photochemical activation modes of (-)-riboflavin, it is possible to sequentially induce isomerization and cyclization by energy transfer (ET) and single-electron transfer (SET) activation pathways, respectively. This catalytic approach has been utilized to emulate the coumarin biosynthesis pathway, which features a key photochemical E → Z isomerization step. Since the ensuing SET-based cyclization eliminates the need for a prefunctionalized aryl ring, this constitutes a novel disconnection of a pharmaceutically important scaffold.
- Metternich, Jan B.,Gilmour, Ryan
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p. 1040 - 1045
(2016/02/05)
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- Simultaneous exploration of TBAF·3H2O as a base as well as a solvating agent for the palladium catalyzed Suzuki cross-coupling of 4-methyl-7-nonafluorobutylsulfonyloxy coumarins under microwave irradiation
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A concise, efficient and facile protocol for the synthesis of a variety of 4-methyl-7-aryl/heteroaryl coumarins has been developed by utilizing the palladium catalyzed Suzuki cross-coupling reaction of 4-methyl-7-nonafluorobutylsulfonyloxy coumarin with a wide range of electronically diverse boronic acids under microwave irradiation. In the presence of a suitable catalyst, ligand and base, the coupling reaction proceeded smoothly to give the biaryls in satisfactory to exceptional yields. The dual role of TBAF·3H2O as a base as well as a solvating agent and the utilization of dppp as a ligand with moderate bite angle (91°) were found to be instrumental for the success of the reaction. Prominent features of this optimization conditions include: shorter reaction times, good to excellent yield and exceptional tolerance to a wide variety of functional groups.
- Joy, M. Nibin,Bodke, Yadav D.,Khader, K.K. Abdul,Sajith, Ayyiliyath M.,Venkatesh, Talavara,Kumar, A.K. Ajeesh
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p. 109 - 120
(2016/01/25)
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- Ytterbium triflate promoted coupling of phenols and propiolic acids: Synthesis of coumarins
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Coumarins are a well-known class of natural occurring and semi-synthetic products with reported important and effective pharmacological activities. In this Letter an improved method for the chemical synthesis of such compounds is described. Coumarins have been obtained in good to excellent yields under microwave irradiation and solvent-free conditions in a short time from differently substituted phenols and propiolic acids used as starting materials in the presence of Yb(OTf)3 hydrate 10% mol as the catalyst.
- Fiorito, Serena,Epifano, Francesco,Taddeo, Vito A.,Genovese, Salvatore
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supporting information
p. 2939 - 2942
(2016/06/14)
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- A solvent-free synthesis of coumarins using 1,3-disulfonic acid imidazolium hydrogen sulfate as a reusable and effective ionic liquid catalyst
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Abstract 1,3-Disulfonic acid imidazolium hydrogen sulfate has been used as an effective and reusable ionic liquid catalyst for the synthesis of coumarins from phenol derivatives with β-ketoesters via the Von Pechmann condensation under solvent-free conditions. This method consistently has the advantages of excellent yields, easy and quick isolation of the products, short reaction times, and green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be recovered and reused for four times without loss of activity.
- Shirini, Farhad,Yahyazadeh, Asieh,Mohammadi, Kamal
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p. 6207 - 6218
(2015/08/18)
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- Environmentally sustainable magnetic solid sulfonic acid: An efficient and reusable catalyst for the Pechmann reaction
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Abstract An environmentally benign sulfonic acid nanocomposite based on Fe3O4@SiO2 core-shell magnetic nanoparticles, Fe3O4@SiO2@Et-PhSO3H, was prepared and the acidity and utility of the catalyst were explored for the synthesis of a diverse range of coumarin derivatives under solvent-free conditions. The catalyst shows potential for scale up in the synthesis of coumarins with high purity and was easily separated by using an external magnet. The recovered catalyst was reused in seven cycles without any significant loss of activity.
- Mobaraki, Akbar,Yasham, Shahriar,Movassagh, Barahman
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supporting information
p. 1263 - 1268
(2015/06/02)
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- Synthesis of substituted coumarins catalyzed by sawdust-SO3H. An efficient and environmentally benign solid acid catalyst under solvent-free conditions
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The sulfonated sawdust (SD-SO3H) was easily prepared by treatment of sawdust, a biomass waste material, with chlorosulfonic acid and characterized by elemental analysis, SEM and TGA. The bio-degradable solid acid catalyst has been applied to the Pechmann condensation reaction of phenols with β-ketoesters for the synthesis of coumarin derivatives under solvent-free conditions. This environmentally benign and inexpensive method has such advantages as simplicity in operation, high yields, low catalyst loading and short reaction time. The catalyst can be efficiently recycled with insignificant loss of activity.
- Tahanpesar,Sarami
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p. 2135 - 2140
(2015/10/29)
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- Synthesis and antibacterial activity of coumarin and its derivatives
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Coumarin and its different derivatives were prepared by treating ethyl acetoacetate with phenol and its different derivatives in acidic media. Product formation was confirmed by spectroscopic techniques i.e. IR, NMR etc. The antimicrobial activities of synthesized compounds were checked against different gram positive and gram negative bacteria by agar ditch method.
- Ali, Zulfiqar,Khalid, Mirza Jnaman,Gilani, Syeda Rubina,Hussain, Habib,Rehman, Hajira,Hussain, Imdad,Sadiqa, Ayesha
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p. 3321 - 3324
(2015/12/05)
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- Handy Protocols using Vinyl Nosylates in Suzuki-Miyaura Cross-Coupling Reactions
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Vinyl nosylates derived from 1,3-dicarbonyl compounds could be engaged in Suzuki-Myaura cross coupling reactions with aryl-, vinyl- and methylboronic acids or trifluoborate derivatives at room temperature in the presence of 2mol% of [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) [PdCl2(dppf)]. One-pot procedures have been set up for practical and efficient nosylation-cross-coupling reactions. Nosylate, as a cheap novel pseudo-halide, gives very stable compounds and is very efficient in Suzuki-Myaura cross coupling reactions (21 examples, 44-99%).
- Dikova, Anna,Cheval, Nicolas P.,Blanc, Aurélien,Weibel, Jean-Marc,Pale, Patrick
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p. 4093 - 4100
(2016/01/25)
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- Rh-Catalyzed Synthesis of Coumarin Derivatives from Phenolic Acetates and Acrylates via C-H Bond Activation
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An efficient annulation strategy involving the reaction of phenolic acetates with acrylates in the presence of [Rh2(OAc)4] as catalyst and formic acid as reducing agent, leading to the high yield synthesis of coumarin derivatives, has been developed. The addition of NaOAc as a base increased the yield of the products. The reaction is quite successful for both electron-rich as well as electron-deficient phenolic acetates, affording coumarins with excellent regioselectivity, and proceeds via C-H bond activation proven by deuterium incorporation studies.
- Gadakh, Sunita K.,Dey, Soumen,Sudalai, Arumugam
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p. 11544 - 11550
(2015/12/04)
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- Synthesis and heterogeneous catalytic activity of covalently immobilized hexamine cation as a magnetically-recoverable nanocatalyst
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Functionalized magnetic core-shell nanoparticles Fe3O4-SiO2-HMTA are prepared by co-precipitation method and characterized by SEM, TEM, FT-IR, XRD, and VSM. The particles are spherical with an average size of approximately 48 nm. The catalytic activity of these nanoparticles was tested in solvent-free synthesis of coumarin derivatives. The catalyst was readily recycled by the use of an external magnetic field and can be reused four times without significant loss of activity or mass.
- Kangari, Sahar,Yavari, Issa,Maasoumi, Bakhshali
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p. 1771 - 1779
(2015/08/06)
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- Cp?Co(III)-Catalyzed Annulations of 2-Alkenylphenols with CO: Mild Access to Coumarin Derivatives
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Cp?Co(III)-catalyzed annulations of 2-alkenylphenols with CO for the synthesis of coumarin derivatives have been developed. The reaction features mild reaction conditions, broad substrate scope, and good functional group tolerance. Preliminary mechanistic studies were conducted, suggesting that C-H activation is the turnover limiting step. Furthermore, the efficiency of this reaction was demonstrated by the rapid total synthesis of three natural products herniarin, xanthyletin, and seselin.
- Liu, Xu-Ge,Zhang, Shang-Shi,Jiang, Chun-Yong,Wu, Jia-Qiang,Li, Qingjiang,Wang, Honggen
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supporting information
p. 5404 - 5407
(2015/11/18)
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- Reduction of substituted phenyl 2-chloroacetates at silver cathodes: Electrosynthesis of coumarins
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To explore the electrosynthesis of coumarins, cyclic voltammetry and controlled-potential (bulk) electrolysis have been employed to investigate the reduction of the carbon-chlorine bond of five substituted phenyl 2-chloroacetates at silver cathodes in dimethylformamide (DMF) containing 0.10 M tetra-n-butylammonium tetrafluoroborate (TBABF4) as supporting electrolyte; the five substrates are 2-formylphenyl 2-chloroacetate (1a), 2-acetylphenyl 2-chloroacetate (2a), methyl 2-(2-chloroacetoxy)benzoate (3a), 2-formyl-5-methoxyphenyl 2-chloroacetate (4a), and 2-formyl-3,5-dimethoxyphenyl 2-chloroacetate (5a). We have examined (a) the effects of substituents on the benzene ring of the substrate as well as the nature of the aryl carbonyl moiety on the formation of the coumarin product and (b) the effect of solvent - namely, DMF, acetonitrile (CH3CN), benzonitrile (PhCN), and propylene carbonate (PC) - and substrate concentration on the yield of the coumarin. It was found that the most unsubstituted substrate (1a) afforded the highest yield (41%) of the desired coumarin in a DMF-TBABF4 medium. A mechanistic scheme is proposed to account for the formation of the coumarin. Furthermore, the only other products seen in these reductions are 2-substituted phenols, which are precursors for synthesis of the various substrates.
- Pasciak, Erick M.,Peters, Dennis G.
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p. G98 - G102
(2015/04/14)
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- Microwave assisted convenient one-pot synthesis of coumarin derivatives via Pechmann condensation catalyzed by FeF3 under solvent-free conditions and antimicrobial activities of the products
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A rapid and efficient solvent-free one-pot synthesis of coumarin derivatives by Pechmann condensation reactions of phenols with ethyl acetoacetate using FeF3 as a catalyst under microwave irradiation is described. This one-pot synthesis on a solid inorganic support provides the products in good yields. The newly synthesized compounds were systematically characterized by IR, 1H-NMR, 13C-NMR, MS and elemental CHN analyses. The proposed solvent-free microwave irradiation method using the environmentally friendly catalyst FeF3 offers the unique advantages of high yields, shorter reaction times, easy and quick isolation of the products, excellent chemoselectivity, and a one-pot, green synthesis. The products were screened for antimicrobial activity, and the results showed that the compounds reacted against all the tested bacteria.
- Vahabi, Vahid,Hatamjafari, Farhad
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p. 13093 - 13103
(2015/02/19)
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- CuFe2O4 nanoparticles: A magnetically recoverable and reusable catalyst for the synthesis of coumarins via pechmann reaction in water
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The synthesis of coumarins by hydroxyalkylation of phenols with ethyl acetoacetate (via Pechmann reaction) is attempted using magnetically separable and reusable CuFe2O4 nanoparticles in water. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.] Copyright
- Baghbanian, Seyed Meysam,Farhang, Maryam
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p. 697 - 706
(2014/01/17)
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- Synthesis of coumarin derivatives using glutamic acid under solvent-free conditions
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An efficient,simple and one-pot protocol for synthesis of coumarin derivatives on the basis condensation reaction of phenols with ethyl acetoacetate employing glutamic acid as a novel catalyst is described.
- Sabetpoor, Setareh,Hatamjafari, Farhad
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p. 863 - 865
(2015/02/02)
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- Recyclable CMK-5 supported sulfonic acid as an environmentally benign catalyst for solvent-free one-pot construction of coumarin through Pechmann condensation
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Sulfonic acid modified nanostructured CMK-5 is used as an alternative to conventional acid catalysts in the von Pechmann condensation of a neat mixture of substituted phenols with ethyl acetoacetate leading to the formation of coumarin derivatives at 130 °C. In comparison, CMK-5-SO3H showed a greater activity than some other homogeneous and heterogeneous catalysts. Additionally, the catalyst is reused repeatedly for 6 reaction cycles without any evidence of loss of activity, confirming the stability of the covalent bonding of acidic centers. The methodology presented offers reusable strategy for the efficient synthesis of coumarin, simplicity in operation, and green aspects by avoiding toxic conventional catalysts and solvents.
- Zareyee, Daryoush,Serehneh, Mahshad
-
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- Lewis acid promoted dual bond formation: Facile synthesis of dihydrocoumarins and spiro-tetracyclic dihydrocoumarins
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Lewis acid (FeCl3) mediated dual bond (C-C and C-O) formation for synthesis of 3,4-dihydrocoumarins is presented. This method has successfully delivered a number of dihydrocoumarins containing dense functionalities on the aromatic ring. Significantly, the present method enabled achieving dihydrocoumarins with tertiary as well as quaternary carbon atoms at the benzylic position. Gratifyingly, the novel spiro-tetracyclic lactones have also been dextrously prepared using this process. the Partner Organisations 2014.
- Niharika, Pedireddi,Ramulu, Bokka Venkat,Satyanarayana, Gedu
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p. 4347 - 4360
(2014/06/23)
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- A rapid and modified approach for C-7 amination and amidation of 4-methyl-7-nonafluorobutylsulfonyloxy coumarins under microwave irradiation
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A facile, efficient and reliable access for the synthesis of an array of 4-methyl-7-(alkyl/aryl/heteroaryl) amino and amido coumarins has been developed by treating 4-methyl-7-nonafluorobutylsulfonyloxy coumarin with various amines and pyridones in presence of a catalyst combination of Pd2(dba) 3/xantphos under microwave irradiation. Nonaflates coupled efficiently to give the diaryl amines in acceptable to excellent yields whereas the corresponding triflate was unstable, yielding the detriflated product as well as the hydrolyzed product as competing side products along with the desired product. The wide bite angle (108°) of xantphos, employment of Cs 2CO3 as a mild base and the utilization of TBAF3H 2O as an additive proved to be key for success of the reaction.
- Joy, M. Nibin,Bodke, Yadav D.,Khader, K. K. Abdul,Ali Padusha, M. Syed,Sajith, Ayyiliyath M.,Muralidharan
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p. 19766 - 19777
(2014/05/20)
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- A rapid approach for the copper, amine, and ligand-free Sonogashira coupling of 4-methyl-7-nonafluorobutylsulfonyloxy coumarins under microwave irradiation
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A rapid, efficient, and reliable access for the synthesis of an assortment of 4-methyl-7-alkyl/aryl/heteroaryl alkynyl coumarins has been developed by the copper, amine, and ligand-free Sonogashira cross-coupling reaction of 4-methyl-7-nonafluorobutylsulfonyloxy coumarin with various terminal alkynes under microwave irradiation. In the presence of a suitable catalyst, base, and solvent, the coupling reaction proceeded smoothly to give the diaryl alkynes in satisfactory to exceptional yields. Nonaflates coupled more efficiently than the corresponding triflates which yielded the detriflated product as well as the hydrolyzed product as competing side products along with the required product. The utilization of TBAF·3H2O as a mild base as well as a solvating agent was the key for success of the reaction.
- Joy, M. Nibin,Bodke, Yadav D.,Abdul Khader,Sajith, Ayyiliyath M.
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p. 2355 - 2361
(2014/05/06)
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- Straightforward assembly of benzoxepines by means of a rhodium(III)- catalyzed C-H functionalization of o-vinylphenols
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Readily available o-vinylphenols undergo a formal (5 + 2) cycloaddition to alkynes when treated with catalytic amounts of [Cp*RhCl2] 2 and Cu(OAc)2. The reaction, which involves the cleavage of the terminal C-H bond of the alkenyl moiety, generates highly valuable benzoxepine skeletons in a practical, versatile, and atom-economical manner. Using carbon monoxide instead of an alkyne as reaction partner leads to coumarin products which formally result from a (5 + 1) cycloaddition.
- Seoane, Andres,Casanova, Noelia,Quinones, Noelia,Mascarenas, Jose L.,Gulias, Moises
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supporting information
p. 834 - 837
(2014/02/14)
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- Magnesium bis(trifluoromethane)sulfonimide: An efficient catalyst for the synthesis of coumarins under solvent-free conditions
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Magnesium bis(trifluoromethane)sulfonimide [Mg(NTf2) 2] is an efficient catalyst for the synthesis of coumarins via the Pechmann condensation reaction of phenols and β-ketoesters under solvent-free conditions.
- Wang, Hongshe
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p. 411 - 414
(2013/05/21)
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- Ultrasound-assisted one-pot synthesis of substituted coumarins catalyzed by poly(4-vinylpyridinium) hydrogen sulfate as an efficient and reusable solid acid catalyst
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Poly(4-vinylpyridinium) hydrogen sulfate solid acid was found to be efficient catalyst for synthesis of substituted coumarins via Pechmann reaction using ultrasound irradiation at room temperature and neat condition in high yields with short reaction times. This methodology offers momentous improvements over various options for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be reused and recovered for several times.
- Khaligh, Nader Ghaffari
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p. 1062 - 1068
(2013/04/24)
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- Introduction of poly(4-vinylpyridinium) perchlorate as a new, efficient, and versatile solid acid catalyst for one-pot synthesis of substituted coumarins under ultrasonic irradiation
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Poly(4-vinylpyridinium) perchlorate, is a supported, recyclable, eco-benign catalyst for synthesis of substituted coumarins via Pechmann reaction using ultrasound irradiation at room temperature and neat condition in high yields with short reaction times. The catalyst was studied by FT-IR, X-ray diffraction, scanning electron microscope, thermo-gravimetric and energy dispersion X-ray analyses. All the products were extensively characterized by 1H NMR, FT-IR, MS and melting point analyses. This methodology offers momentous improvements over various options for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be reused and recovered for several times without loss of activity.
- Khaligh, Nader Ghaffari,Shirini, Farhad
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p. 26 - 31,6
(2012/12/11)
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- Succinimide-N-sulfonic acid catalyzed synthesis of bis(indolyl)methane and coumarin derivatives under mild conditions
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A mild and simple procedure is described for the synthesis of bis(indolyl)methane and coumarin derivatives using succinimide-N-sulfonic acid as an efficient, cheap, and reusable catalyst under mild conditions.
- Shirini, Farhad,Khaligh, Nader Ghaffari
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p. 1890 - 1896
(2013/11/19)
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- An environmentally friendly, chemoselective, and efficient protocol for the preparation of coumarin derivatives by Pechman condensation reaction using new and reusable heterogeneous Lewis acid catalyst polystyrene-supported GaCl 3
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An environmentally benign Pechman protocol for the one-pot synthesis of 4-substituted coumarins through the condensation reactions of phenol substrates with β-ketoesters using polystyrene-supported GaCl3 (PS-GaCl3) as a highly active and reusable solid Lewis acid catalyst under mild and heterogeneous conditions in good to excellent yields is described. This new protocol is easy, simple, cost-effective, chemoselective, and in addition has the advantages of easy availability, stability, reusability and eco-friendly character of the catalyst, high to excellent yields, simple experimental and work-up procedure.
- Rahmatpour, Ali,Mohammadian, Sara
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p. 271 - 278
(2013/05/08)
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- Br?nsted-acidic imidazolium ionic liquid [bmim(SO 3H)][OTf]: A mild catalyst for highly efficient synthesis of coumarins
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The use of Br?nsted-acidic imidazolium ionic liquid [bmim(SO 3H)][OTf] as a catalyst for the high yielding synthesis of a wide variety of coumarins under mild conditions via Pechmann condensation has been demonstrated. This method is simple and has benefits from the easy way to isolate coumarins in good yields. In comparison with the classical Pechmann condensation, this new method consistently has the advantage of high yields and good purity.
- Haldorai, Yuvaraj,Kalkhambkar, Rajesh G.,Shim, Jae-Jin
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p. 9379 - 9383
(2013/11/19)
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- Synthesis of coumarins via PIDA/I2-mediated oxidative cyclization of substituted phenylacrylic acids
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A variety of functionalized coumarins were synthesized from substituted phenylacrylic acids via PIDA/I2-mediated and irradiation-promoted oxidative carbon-oxygen bond formation. Our studies show that the oxygen in the pendant carboxylic acid group cyclizes favorably to the aryl ring that is cis to it. The main advantages of this method include good functional group tolerance and the transition-metal-free characteristic. The Royal Society of Chemistry 2013.
- Li, Jinming,Chen, Huiyu,Zhang-Negrerie, Daisy,Du, Yunfei,Zhao, Kang
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p. 4311 - 4320
(2013/04/24)
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