Glaser Coupling Reaction Research Articles

Organic transformations catalyzed by palladium nanoparticles on carbon nanomaterials

An efficient C–C bond coupling reactions (Suzuki–Miyaura and Glaser) catalyzed by PdO/GO nano-catalyst is presented. In addition, PdO/MWCNT nano-catalyst-mediated domino one-pot synthesis of 2-alkyl/2-aryl benzofurans has been accomplished from 2-iodophenols and terminal alkynes. The formation of benzofurans proceeds through intermolecular Sonogashira reaction followed by intramolecular nucleophilic addition of internal hydroxyl group onto the acetylenic bond. The catalyst PdO/GO has been reused successfully, with nearly no loss of activity up to 5 cycles. Synopsis: An efficient PdO/GO and PdO/MWCNT nanocatalysts have been developed for C–C coupling reactions like Suzuki and Glaser coupling reactions, multi-catalytic one-pot synthesis of 2-aryl, 2-alkyl benzofurans staring from 2-iodophenols and terminal alkynes. The protocol involves formation of benzofuran derivatives, i.e., Sonogashira reaction followed by 2-ethynyl phenol cyclization..

Catalysis of photooxidation reactions through transformation between Cu2+ and Cu+ in TiO2-Cu-MOF composites.

Novel porous TiO2@Cu3(BTC)2 composites, which were synthesized using ionic liquids (ILs) as solvents, exhibited excellent activity for photooxidation of styrene to 4-aryl tetralones and promoting the Glaser coupling reaction with O2 under light irradiation. It was discovered that the transformation between Cu2+ and Cu+ was crucial for enhancing the photocatalytic performance.

Interfacial Synthesis of Conjugated Two-Dimensional N-Graphdiyne.

We explored the interfacial synthesis of 2D N-graphdiyne films at the gas/liquid and liquid/liquid interfaces. Triazine- or pyrazine-based monomers containing ethynyl group were polymerized through the Glaser coupling reactions at interfaces. Several layered, highly ordered and conjugated 2D N-graphdiyne were obtained. Their structures were characterized by TEM, SEM, AFM, XPS, and Raman spectra. Thin films with minimum thickness of 4 nm could be prepared.

Polyethylene‐Based Tadpole Copolymers

Novel well‐defined polyethylene‐based tadpole copolymers {(c‐PE)‐b‐PS, PE: polyethylene, PS: polystyrene} with ring PE head and linear PS tail are synthesized by combining polyhomologation, atom transfer radical polymerization (ATRP), and Glaser coupling reaction. The OH groups of the 3‐miktoarm star copolymers (PE‐OH)2‐b‐PS, synthesized by polyhomologation and ATRP, are transformed to alkyne groups by esterification with propiolic acid, followed by Glaser cyclization and removal of the unreacted linear with Merrifield's resin–azide. The characterization results of intermediates and final products by high‐temperature size exclusion chromatography, 1H NMR spectroscopy, and differential scanning calorimetry confirm the tadpole topology. image

A triptycene-based two-dimensional porous organic polymeric nanosheet

A new application of the “old” Glaser coupling reaction for a two-dimensional porous polymeric nanosheet on an air/liquid interface is developed.

Intramolecular Electronic Coupling in the Thiophene-Bridged Carbazole-Based Diporphyrin.

The Glaser coupling reaction of ethynyl-substituted carbazole-based isophlorins provided butadiyne-bridged dimers, which were transformed into the thiophene-bridged dimers via the annulation reaction. Oxidation of these isophlorin dimers afforded carbazole-based diporphyrins. Notable electronic interactions in the diporphyrins have been confirmed by means of UV/vis-near-infrared (NIR) absorption spectroscopy, cyclic voltammetry (CV) measurements, and density functional theory (DFT) calculations.

Well-Defined Cyclic Triblock Terpolymers: A Missing Piece of the Morphology Puzzle.

Two well-defined cyclic triblock terpolymers, missing pieces of the terpolymer morphology puzzle, consisting of poly(isoprene), polystyrene, and poly(2-vinylpyridine), were synthesized by combining the Glaser coupling reaction with anionic polymerization. An α,ω-dihydroxy linear triblock terpolymer (OH-PI1,4-b-PS-b-P2VP-OH) was first synthesized followed by transformation of the OH to alkyne groups by esterification with pentynoic acid and cyclization by Glaser coupling. The size exclusion chromatography (SEC) trace of the linear terpolymer precursor was shifted to lower elution time after cyclization, indicating the successful synthesis of the cyclic terpolymer. Additionally, the SEC trace of the cyclic terpolymer produced, after cleavage of the ester groups, shifted again practically to the position corresponding to the linear precursor. The first exploratory results on morphology showed the tremendous influence of the cyclic structure on the morphology of terpolymers.

Water-dispersible Hollow Microporous Organic Network Spheres as Substrate for Electroless Deposition of Ultrafine Pd Nanoparticles with High Catalytic Activity and Recyclability.

Microporous organic networks (MONs) have been considered as an ideal substrate to stabilize active metal nanoparticles. However, the development of highly water-dispersible hollow MONs nanostructures which can serve as both the reducing agent and stabilizer is highly desirable but still challenging. Here we report a template-assisted method to synthesize hollow microporous organic network (H-MON) spheres using silica spheres as hard template and 1,3,5-triethynylbenzene as the building blocks through a Glaser coupling reaction. The obtained water-dispersible H-MON spheres bearing sp- and sp2 -hybridized carbon atoms possess a highly conjugated electronic structure and show low reduction potential; thus, they can serve as a reducing agent and stabilizer for electroless deposition of highly dispersed Pd clusters to form a Pd/H-MON spherical hollow nanocomposite. Benefitting from their high porosity, large surface area, and excellent solution dispersibility, the as-prepared Pd/H-MON hollow nanocomposite exhibits a high catalytic performance and recyclability toward the reduction of 4-nitrophenol.

ChemInform Abstract: Sequential Sonogashira and Glaser Coupling Reactions: Facile Access to 1,4‐Disubstituted 1,3‐Butadiynes from Arylbromide.

Abstract1‐Aryl‐2‐trimethylsilylethynes, prepared in situ via Sonogashira coupling, undergo base promoted homocoupling to form 1,3‐butadiynes in moderate yields.

CoIII(cyclam) Oligoynyls: Monomeric Oligoynyl Complexes and Dimeric Complexes with an Oligoyn-diyl Bridge

Described in this work are the preparation and characterization of an extensive family of CoIII(cyclam)-oligoynyl compounds (cyclam = 1,4,8,11-tetraazacyclotetradecane) and elucidation of their electronic structures through DFT calculations. Monomeric Co compounds bearing one oligoynyl, namely, [Co(cyclam)(C2nR)Cl]+ with n = 1–3, and two butadiynyls [Co(cyclam)(C4H)2]+ were prepared from the reactions between [Co(cyclam)Cl2]Cl, Et3N or Et2NH, and the corresponding alkynes. The oligoyndiyl-bridged (μ-C2m) dimers of CoIII(cyclam)Cl with m = 2 and 3 were prepared via the same process by varying alkyne stoichiometry, while those with m = 4 and 6 were prepared using the Glaser coupling reaction. The complexes were prepared in moderate yield (with the exception of m = 6) under mild conditions without requiring an anaerobic or anhydrous environment and are generally stable toward ambient atmosphere. Voltammetric analysis of the dimeric complexes revealed a weak Co–Co interaction through the bridge, which is atte...

Sequential Sonogashira and Glaser coupling reactions: facile access to 1,4-disubstituted 1,3-butadiynes from arylbromide

A simplified synthesis of symmetrical 1,4-disubstitued 1,3-butadiynes was developed using a sequential two-step process combining a typical Sonogashira coupling with a Glaser coupling. The Sonogashira reaction coupled arylbromide and trimethylsilylacetylene. In the second step, a Glaser coupling reaction was performed using the crude trimethyl(arylethynyl)silane product from the previous Sonogashira coupling in a basic solvent; the Glaser coupling proceeded to completion without the addition of extra Pd or Cu catalysts. The catalytic amount of metal (Cu and Pd) in the second step was substantially less than that used in a typical Glaser coupling reaction.

Efficient and environmentally friendly Glaser coupling of terminal alkynes catalyzed by multinuclear copper complexes under base-free conditions

An efficient catalytic system with multinuclear copper complexes as catalysts has been developed for the aerobic Glaser coupling reaction, which adopts environmentally friendly water as the solvent at room temperature under base-free condition.

Lattice-Directed Formation of Covalent and Organometallic Molecular Wires by Terminal Alkynes on Ag Surfaces.

Surface reactions of 2,5-diethynyl-1,4-bis(phenylethynyl)benzene on Ag(111), Ag(110), and Ag(100) were systematically explored and scrutinized by scanning tunneling microscopy, molecular mechanics simulations, and density functional theory calculations. On Ag(111), Glaser coupling reaction became dominant, yielding one-dimensional molecular wires formed by covalent bonds. On Ag(110) and Ag(100), however, the terminal alkynes reacted with surface metal atoms, leading to one-dimensional organometallic nanostructures. Detailed experimental and theoretical analyses revealed that such a lattice dependence of the terminal alkyne reaction at surfaces originated from the matching degree between the periodicities of the produced molecular wires and the substrate lattice structures.

Preparation of Multivalent Carbohydrate Mimetics Based on Enantiopure 1,2‐Oxazines by Sonogashira Coupling and Subsequent Reductive Ring‐Opening

AbstractA modular approach to aryl C‐glycosides and their multivalent analogues is presented. Sonogashira coupling reactions connected the key compounds, enantiopure bicyclic 1,2‐oxazine derivatives bearing p‐bromophenyl substituents, with alkynes. Subsequent hydrogenolyses or a combination of hydrogenolysis and samarium diiodide mediated reductions converted the coupling products into new unnatural amino carbohydrate mimetics with a D‐talose configuration. By Glaser coupling reactions we obtained products with a 1,3‐diyne linker and divalent compounds derived therefrom. Through Sonogashira reactions of compound 8 with several iodobenzene derivatives, di‐, tri‐, and tetravalent compounds were prepared in high yields. The subsequent reductive processes converted the 1,2‐oxazine moieties into the corresponding aminopyrans. Severe purification problems were solved in most cases by following the appropriate strategies as an apt sequence of steps or by acetylation of the intermediates.

ChemInform Abstract: Recent Advances and Applications of Glaser Coupling Employing Greener Protocols

AbstractReview: 109 refs.

Synthesis of a sun-shaped amphiphilic copolymer consisting of a cyclic perfluorocyclobutyl aryl ether-based backbone and lateral PMAA side chains

A novel amphiphilic sun-shaped copolymer, c-PMBTFVB-g-PMAA (MBTFVB: 2-methyl-1,4-bistrifluorovinyloxybenzene, MAA: methacrylic acid) containing a cyclic perfluorocyclobutyl (PFCB) aryl ether-based backbone and PMAA lateral side chains with narrow molecular weight distribution (Mw/Mn ≤ 1.38), was synthesized via the site transformation strategy. First, a PMBTFVB linear precursor was prepared by thermal step-growth cycloaddition polymerization of MBTFVB trifluorovinyl monomer. After the end functionalization of the linear precursor with alkyne, Glaser coupling reaction was performed to produce c-PMBTFVB cyclic homopolymer. The pendant methyls on PFCB aryl ether-based backbone were then converted to Br-containing ATRP initiating groups by a mono-bromination reaction with N-bromosuccinimide (NBS) and benzoyl peroxide (BPO) to give c-PMBTFVB-Br cyclic macroinitiator without affecting the main chain, where the density of ATRP initiation groups could be tuned from 33% to 58% by varying the feeding ratio of NBS to the pendant methyl. Subsequently, c-PMBTFVB-g-PMAA sun-shaped amphiphilic copolymers with hydrophilic PMAA side chains were synthesized by ATRP of tert-butyl methacrylate (tBMA) initiated by c-PMBTFVB-Br, followed by the selective hydrolysis of hydrophobic PtBMA segment into hydrophilic PMAA segment using CF3COOH. The obtained c-PMBTFVB cyclic homopolymer and its precursor were well characterized by GPC, NMR, and DSC and all the observations indicated a high efficiency of the intra-macromolecular cyclization via Glaser coupling reaction. The critical micelle concentrations of the obtained amphiphilic copolymers were determined by fluorescence probe technique and the morphologies of the formed micelles were investigated by TEM.

Diruthenium-polyyn-diyl-diruthenium wires: electronic coupling in the long distance regime.

Reported herein is a series of Ru2(Xap)4 capped polyyn-diyl compounds, where Xap is either 2-anilinopyridinate (ap) or its aniline substituted derivatives. Symmetric [Ru2(Xap)4](μ-C4k)[Ru2(Xap)4] (compounds 4ka (X = 3-isobutoxy) and 4kc (X = 3,5-dimethoxy) with k = 2, 3, 4, and 5) was obtained from the Glaser coupling reaction of Ru2(Xap)4(C2kH). Unsymmetric [Ru2(Xap)4](μ-C(4k+2))[Ru2(ap)4] (compounds 4k+2b with k = 2, 3, and 4) were prepared from the Glaser coupling reaction between Ru2(Xap)4(C(2k+2)H) and Ru2(ap)4(C2kH). X-ray diffraction study of compound 12c revealed both the sigmoidal topology of the polyyn-diyl bridge and the fine structural detail about the Ru2 cores. Cyclic and differential pulse voltammetric (CV and DPV) measurements and spectroelectrochemical studies revealed that (i) the reduced monoanions [Ru2-C2m-Ru2](-1) (m = 4-8) belong to the Robin-Day class II mixed valent ions and (ii) the electronic coupling between Ru2 termini depends on the length of the polyyn-diyl bridge with an attenuation constant (γ) between 0.12 and 0.15 Å(-1). In addition, spin-unrestricted DFT calculations provide insight about the nature of orbitals that mediate the long distance electronic coupling.

One-pot esterification-click (CuAAC) and esterification–acetylene coupling (Glaser/Eglinton) for functionalization of Wang polystyrene resin

We report three new sets of one-pot reactions for functionalization of Wang polystyrene resin and its derivatives. We first show that it is possible to combine esterification and CuAAC (Copper-Catalyzed Alkyne-Azide Cycloaddition) in a one-pot reaction with a very high yield. We also demonstrate for the first time that it is possible to combine esterification with either Glaser or Eglinton acetylene-couplings in a one-pot reaction. Finally, we show that the esterification, CuAAC, and Glaser-coupling reactions are all compatible with each other, and it is possible to run in parallel esterification/CuAAC and esterification/Glaser coupling in a single vessel. All reactions are performed at room temperature while the only separation method required is filtering and washing the resin.

Synthesis of branch-ring-branch tadpole-shaped [linear-poly(ε-caprolactone)]-b-[cyclic-poly(ethylene oxide)]-b- [linear-poly(ε-caprolactone)] by combination of glaser coupling reaction with ring-opening polymerization

A novel amphiphilic branch-ring-branch tadpole- shaped (linear-poly(e-caprolactone))-b-(cyclic-poly(ethylene ox- ide))-b-(linear-poly(e-caprolactone)) ((l-PCL)-b-(c-PEO)-b-(l-PCL)) was synthesized by combination of glaser coupling reaction with ring-opening polymerization (ROP) mechanism. The self- assembling behaviors of (l-PCL)-b-(c-PEO)-b-(l-PCL) and their p- shaped analogs of poly(e-caprolactone)/poly (ethylene oxide))- b-poly(ethylene oxide)-b-(poly(e-caprolactone)/poly(ethylene ox- ide) with comparable molecular weight in water were prelimi- narily investigated. The results showed that the micelles formed from the former took a fiber look, however, that formed from the latter took a spherical look. V C 2012 Wiley Peri- odicals, Inc. J Polym Sci Part A: Polym Chem 50: 3095-3103, 2012

Synthesis of twin‐tail tadpole‐shaped (cyclic polystyrene)‐ block‐[linear poly (tert‐butyl acrylate)]2 by combination of glaser coupling reaction with living anionic polymerization and atom transfer radical polymerization

AbstractThe twin‐tail tadpole‐shaped (cyclic polystyrene)‐block‐[linear poly (tert‐butyl acrylate)]2 [(c‐PS)‐b‐(l‐PtBA)2] was synthesized by combination of Glaser coupling reaction with atom transfer radical polymerization (ATRP) and living anionic polymerization (LAP). First, the telechelic PS with an active and an ethoxyethyl‐protected hydroxyl groups at both ends was prepared by LAP of St monomers using lithium naphthalenide as initiator and terminated by 1‐ethoxyethyl glycidyl ether. And the alkyne groups were introduced onto each PS end by selectively reaction of active hydroxy group with propargyl bromide in NaH/tetrahydrofuran (THF) system. Then, the intramolecular cyclization was carried out by Glaser coupling reaction in pyridine/Cu(I)Br system in air atmosphere. Finally, the macroinitiator of c‐PS with two bromine groups at the junction point was synthesized via the cleavage of ethoxyethyl group and the subsequent esterification of the deprotected hydroxyl groups with 2‐bromoisobutyryl bromide. The copolymer of (c‐PS)‐b‐(l‐PtBA)2 was obtained by ATRP of tBA monomers, and the PtBA segment was also hydrolyzed for (cyclic polystyrene)‐block‐(linear polyacrylic acid)2 [(c‐PS)‐b‐(l‐PAA)2]. The target copolymers and all intermediates were well characterized by GPC, MALDI‐TOF MS, and 1H NMR in detail. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012