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Terminal Alkynes (terminal + alkyne)
Selected AbstractsA Highly Efficient Three-Component Coupling of Aldehyde, Terminal Alkyne, and Amine via C,H Activation Catalyzed by Reusable Immobilized Copper in Organic,Inorganic Hybrid Materials under Solvent-Free Reaction Conditions.CHEMINFORM, Issue 40 2007Pinhua Li Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Palladium(II) Chloride and a (Dipyridin-2-ylmethyl)amine-Derived Palladium(II) Chloride Complex as Highly Efficient Catalysts for the Synthesis of Alkynes in Water or in NMP and of Diynes in the Absence of ReoxidantEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2005Juan Gil-Moltó Abstract The (dipyridin-2-ylmethyl)amine-derived palladium chloride complex 1 and PdCl2 are efficient catalysts for cross-coupling reactions between terminal alkynes and aryl iodides or bromides under modified Sonogashira,Cassar,Heck conditions. The alkynylation can be performed under copper-free conditions in water at reflux or at room temperature under air with pyrrolidine as base and tetra- n -butylammonium bromide (TBAB) as additive, with TONs of up to 7,×,104 and TOFs(h,1) of up to 6666. Terminal alkynes can be arylated in NMP as well under copper- and amine-free conditions at 110 °C or room temperature, with tetra- n -butylammonium acetate (TBAA) acting as base with TONs up to 2,×,105 and TOFs (h,1) up to 66,666. In general, complex 1 displays a slightly higher efficiency than PdCl2 as catalyst and maintains the same activity after five consecutive runs. Alternatively, these alkynylation processes can be carried out under microwave heating conditions. The homocoupling of terminal alkynes to the corresponding 1,3-diynes proceeds under phosphane-free conditions with the (dipyridin-2-ylmethyl)amine-derived palladium chloride complex 1 or with PdCl2 as catalysts and with CuI as cocatalyst in NMP with use of either TBAA or pyrrolidine as bases. This Glaser-type reaction can be performed at 110 °C or at room temp. in the presence of air without the use of a reoxidant. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Dihydroazulene Photoswitches: The First Synthetic Protocol for Functionalizing the Seven-Membered RingEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2009Michael Ĺxman Petersen Abstract The first synthetic protocol for functionalizing the dihydroazulene (DHA) photoswitch in its seven-membered ring has been developed. This protocol is based on regioselective bromination, followed by regioselective elimination of HBr, and finally a palladium-catalyzed cross-coupling reaction with a terminal alkyne. The position of functionalization (C-7) was confirmed by X-ray crystal structure analysis. Light-induced ring opening of this compound to its vinylheptafulvene (VHF) isomer followed by thermal ring closure provides a mixture of two DHA regioisomers in a ratio that depends on the wavelength of irradiation and solvent polarity.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis of Lanthanide(III) Chelates by Using ,Click' ChemistryHELVETICA CHIMICA ACTA, Issue 3 2007Janne Ketola Abstract The copper(I)-catalyzed dipolar [2+3] cycloaddition reaction of an azide and a terminal alkyne is exploited in the preparation of various europium(III), terbium(III), and dysprosium(III) chelates (Schemes,1,3). By changing the nature of the alkyne and the azide, a wide range of chelates and biomolecule-labeling reactants were obtained. The photophysical properties (Table) of the synthesized chelates are also discussed. [source] A Novel Coupling 1,3-Dipolar Cycloaddition Sequence as a Three-Component Approach to Highly Fluorescent IndolizinesHELVETICA CHIMICA ACTA, Issue 7 2005Alexandru Indolizines 4 and biindolizines 6 can be synthesized in moderate yields in a consecutive one-pot three-component process by a coupling/1,3-dipolar cycloaddition sequence of a (hetero)arenecarbonyl chloride 1, a terminal alkyne 2, and a suitable 1-(2-oxoethyl) pyridinium bromide 3 or 5, respectively (Schemes,1 and 2). After the Sonogashira coupling, a [2+3] cycloaddition of the in situ formed pyridinium ylide, an allyl-type 1,3-dipole, furnishes a cycloadduct that is instantaneously oxidatively aromatized to give the highly fluorescent indolizine derivatives that were unambiguously characterized by an X-ray-structure analysis of compound 4d (Fig.,1). Additionally, fluorescence studies with pyridinyl-substituted representatives reveal not only that indolizines and biindolizines are highly interesting fluorescence dyes but that their fluorescence color can also be reversibly switched upon altering the pH of the medium. [source] Well-Defined Regioselective Iminopyridine Rhodium Catalysts for Anti-Markovnikov Addition of Aromatic Primary Amines to 1-OctyneADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009Carlos Alonso-Moreno Abstract A series of cationic rhodium(I) complexes of the type [Rh(N-N)(COD)][BPh4], containing the following iminopyridine-based bidentate nitrogen donor ligands (N-N): 2,6-diisopropyl- N -[1-(pyridin-2-yl)ethylidene]aniline (dipea, 1), 2,6-dimethyl- N -[1-(pyridin-2-yl)ethylidene]aniline (dmpea, 2), 2,4,6-trimethyl- N -[1-(pyridin-2-yl)ethylidene]aniline (tmpea, 3) and 2,6-diisopropyl- N -[1-(4-methylpyridin-2-yl)ethylidene]aniline] (dipmpea, 4), were synthesized and fully characterized. The intermolecular hydroamination of a terminal alkyne, such as 1-octyne, with primary aromatic amines in the presence of these cationic rhodium(I) catalysts occurred in an anti-Markovnikov fashion. The rhodium complexes catalyzed the regioselective formation of the E- isomer of the corresponding imine, without the formation of the Z -isomer or the Markovnikov product. These compounds are also presented as efficient regioselective catalysts for the hydroamination of anilines in the presence of air and/or water. [source] Cyclic alkoxyamine-initiator tethered by azide/alkyne-"click"-chemistry enabling ring-expansion vinyl polymerization providing macrocyclic polymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2010Atsushi Narumi Abstract A cyclic initiator for the nitroxide-mediated controlled radical polymerization (NMP) is a powerful tool for the preparation of macrocyclic polymers via a ring-expansion vinyl polymerization mechanism. For this purpose, we prepared a Hawker-type NMP-initiator that includes an azide and a terminal alkyne as an acyclic precursor, which is subsequently tethered via an intramolecular azide/alkyne-"click"-reaction, producing the final cyclic NMP-initiator. The polymerization reactions of styrene with cyclic initiator were demonstrated and the resultant polymers were characterized by the gel permeation chromatography (GPC) and the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). These results prove that the ring-expansion polymerization of styrene occurred together with the radical ring-crossover reactions originating from the exchange of the inherent nitroxides generating macrocyclic polystyrenes with higher expanded rings. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3402,3416, 2010 [source] 2,3,4,6-Tetra- O -acetyl-,- d -glucopyranosyl azideACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2008Simone Dedola The CuI -catalysed 1,3-dipolar cycloaddition of an azide and a terminal alkyne is becoming an increasingly popular tool for synthetic chemists. This is the most representative of the so-called `click reactions' and it is used to generate 1,4-disubstituted triazoles in high yield. During studies on such cycloaddition reactions, a reduced reactivity of an ,-glucosyl azide with respect to the corresponding ,-anomer was observed. With the aim of understanding this phenomenon, the structure of the title compound, C14H19N3O9, has been determined at 140,K. The glucopyranosyl ring appears in a regular 4C1 chair conformation with all the substituents in equatorial positions, except for the anomeric azide group, which adopts an axial orientation. The observed bond lengths are consistent with a strong anomeric effect, which is reflected in a change in dipolar character and hence reduced reactivity of the ,-glucosyl azide. [source] ChemInform Abstract: Rhodium-Catalyzed Chemo- and Stereoselective Arylative and Alkenylative Cyclization Reactions of Unsymmetric Diynes Containing a Terminal Alkyne Moiety with Organoboronic Acids.CHEMINFORM, Issue 38 2010Levent Artok Abstract A variety of 1,6-diynes containing a terminal alkyne, e.g. (I) or (IV), reacts with aryl- (II) or alkenylboronic acids (VI) with excellent chemo- and stereoselectivity in the presence of a Rh2(cod)2(O-Me)2 complex to give the 5-exo cyclization products, exclusively. [source] A One-Pot Synthesis of Constitutionally Unsymmetrical Rotaxanes Using Sequential CuI -Catalyzed Azide,Alkyne CycloadditionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2008Jason Abstract A one-pot sequential CuI -catalyzed azide,alkyne cycloaddition (CuAAC) strategy is presented for the synthesis of constitutionally unsymmetrical cyclobis(paraquat- p -phenylene)-based rotaxanes in good yields from simple starting materials. The methodology consists of performing multiple CuAAC reactions to stopper a pseudorotaxane in a stepwise manner, the order of which is controlled through silyl-protection and AgI -catalyzed deprotection of a terminal alkyne. The methodology is highlighted by the synthesis of an amphiphilic branched [4]rotaxane. The methodology increases the ability to access ever more complicated mechanically interlocked compounds to serve in devices as sophisticated and functional molecular machinery. [source] Regiospecific Three-Component Access to Fluorescent 2,4-Disubstituted Quinolines via One-Pot Coupling-Addition-Cyclocondensation-Sulfur Extrusion Sequence,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2010Sven Rotzoll Abstract 2,4-Di- and 2,4,7-trisubstituted quinolines are readily synthesized in a regioselective fashion from acyl chlorides, terminal alkynes, and 2-aminothiophenols by a consecutive, microwave-assisted one-pot three-component Sonogashira coupling-Michael addition,cyclocondensation sequence and following sulfur extrusion in moderate to good yields. The terminal sulfur extrusion step was studied by DFT computations. The absorption spectra of 2,4-disubstituted quinolines can be rationalized by DFT-ZINDO-CI calculations and all derivatives show intense blue emission upon UV excitation. [source] Radical Addition of Ethers to Terminal Alkynes with High E -SelectivityEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 30 2009Zili Chen Abstract Direct radical additions of ethers to terminal alkynes were investigated by using Me2Zn/O2 as radical initiator to afford 2-vinyl ether derivatives with high E -selectivity, while reversed E/Z selectivity is obtained with Et3B/O2. Two competitive pathways are suggested for the formation of vinyl radical B: zinc-radical exchange (route a) followed by protonation provides E -configuration products exclusively through Zn(II) complexation. Hydrogen abstraction by vinyl radicals (route b) yields mainly Z isomers.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Regioselective Metal-Catalyzed Hydrophosphinylation of Alkynes: Synthesis of Enantiopure ,- or ,-Substituted Vinylphosphane OxidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 26 2009Amélie Duraud Abstract Palladium was found to catalyze regioselective Markovnikov addition of chiral enantiopure 1r -oxo-2c,5t -diphenylphospholane (1) to terminal alkynes, whereas rhodium catalysis offers selectively the (E)-anti-Markovnikov adduct. This strategy offers rapid access to chiral and enantiopure ,- or ,-substituted-1-alkenylphospholanes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] The Use of a Bifunctional Copper Catalyst in the Cross-Coupling Reactions of Aryl and Heteroaryl Halides with Terminal AlkynesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2008Minyan Wu Abstract Copper-catalyzed cross-coupling reactions of aryl halides and heteroaryl halides with terminal alkynes were carried out in DMF at 110,130 °C to provide the corresponding coupling products in satisfactory-to-good yields by using inexpensive 8-hydoxyquinoline as the ligand. Noteworthy is that the bifunctional copper catalyst was successfully applied in this alkynylation reaction for the first time.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Palladium(II) Chloride and a (Dipyridin-2-ylmethyl)amine-Derived Palladium(II) Chloride Complex as Highly Efficient Catalysts for the Synthesis of Alkynes in Water or in NMP and of Diynes in the Absence of ReoxidantEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2005Juan Gil-Moltó Abstract The (dipyridin-2-ylmethyl)amine-derived palladium chloride complex 1 and PdCl2 are efficient catalysts for cross-coupling reactions between terminal alkynes and aryl iodides or bromides under modified Sonogashira,Cassar,Heck conditions. The alkynylation can be performed under copper-free conditions in water at reflux or at room temperature under air with pyrrolidine as base and tetra- n -butylammonium bromide (TBAB) as additive, with TONs of up to 7,×,104 and TOFs(h,1) of up to 6666. Terminal alkynes can be arylated in NMP as well under copper- and amine-free conditions at 110 °C or room temperature, with tetra- n -butylammonium acetate (TBAA) acting as base with TONs up to 2,×,105 and TOFs (h,1) up to 66,666. In general, complex 1 displays a slightly higher efficiency than PdCl2 as catalyst and maintains the same activity after five consecutive runs. Alternatively, these alkynylation processes can be carried out under microwave heating conditions. The homocoupling of terminal alkynes to the corresponding 1,3-diynes proceeds under phosphane-free conditions with the (dipyridin-2-ylmethyl)amine-derived palladium chloride complex 1 or with PdCl2 as catalysts and with CuI as cocatalyst in NMP with use of either TBAA or pyrrolidine as bases. This Glaser-type reaction can be performed at 110 °C or at room temp. in the presence of air without the use of a reoxidant. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Simple Derivatives of Natural Amino Acids as Chiral Ligands in the Catalytic Asymmetric Addition of Phenylacetylene to AldehydesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2005Zhi-jian Han Abstract Optically active propargylic alcohols are important chiral building blocks in asymmetric synthesis, and asymmetric addition of terminal alkynes to aldehydes is one of the most important and interesting procedures by which to prepare these chiral building blocks. In this work we have identified some simple derivatives of (S)-proline and other natural amino acids as chiral ligands that can be combined with Ti(OiPr)4 and then used to catalyze the asymmetric addition of zinc acetylide, produced in situ by the reaction of phenylacetylene with diethylzinc, to aldehydes. The ee value was as high as 90,%. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] One-Pot Synthesis of Quinoline Derivatives Directly from Terminal Alkynes via Sequential Ruthenium(II) and Acid CatalysisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Min Zhang Abstract A convenient one-pot synthesis of 2,3-disubstituted, 2,3,6-trisubstituted, and 2,3,6,7-tetrasubstituted quinoline analogues from terminal alkynes via sequential ruthenium(II) and para -toluenesulfonic acid (p -TSA) co-catalyzed reactions is described. The catalytic process is shown to take place first via intermediate formation of an allyl ketone and then addition of an aniline derivative to the allyl ketone. The p -TSA is a catalyst for both allyl ketone and quinoline synthetic steps. The method allowed us to synthesize a wide range of quinoline derivatives and introduce different substituents by employing various simple starting materials. The reaction allows the synthesis of halogen-containing products. [source] Efficient Synthesis of 2-Fluoromethylated Quinolines via Copper-Catalyzed Alkynylation and Cyclization of Fluorinated Imidoyl IodidesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Shan Li Abstract 2-Fluoromethylated quinolines were synthesized through the reaction of N -aryl-fluorinated imidoyl iodides with terminal alkynes in good yields by the catalysis of copper(I) iodide (CuI) alone. [source] Copper-Catalyzed Three-Component Synthesis of 2-Iminodihydrocoumarins and 2-IminocoumarinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Yang Shen Abstract An efficient synthesis of N -sulfonyl-substituted 2-imino-3,4-dihydrocoumarins and 2-iminocoumarins via a copper-catalyzed multicomponent reaction of sulfonyl azides with terminal alkynes and ,-(ortho -hydroxyphenyl)-,,,-unsaturated ketones or ortho -hydroxyphenylpropiolates has been developed. The cascade process involves trapping the keteimine by a nucleophilic addition and an intramolecular Michael addition. This methodology could well be extended to the concise synthesis of the polysubstituted piperidine scaffold. [source] Highly Efficient Copper-Catalyzed Synthesis of Internal Alkynes via Aerobic Oxidative Arylation of Terminal AlkynesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Honghua Rao Abstract We have developed a novel and highly efficient, copper-catalyzed synthesis of internal alkynes via oxidative couplings of aromatic boronic acids with terminal alkynes at room temperature. The protocol uses inexpensive copper(I) oxide [Cu2O] as the catalyst, oxygen in the air as the stoichiometric oxidant; no ligand and sealed reaction vessels are required, and remarkable functional group tolerability is observed with coupling occurring. [source] Copper-in-Charcoal-Catalyzed, Tandem One-Pot Diazo Transfer-Click ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Ching-Tien Lee Abstract Copper-in-charcoal (Cu/C) is an effective heterogeneous catalyst for tandem diazo transfer/click reactions. In the presence of Cu/C, various azides can be generated in situ from the corresponding amines, and subsequently undergo [3+2],cycloaddition with terminal alkynes to afford triazoles in good yields. The catalyst is also easily recycled. [source] Gold- and Silver-Catalyzed Intramolecular Hydroamination of Terminal Alkynes: Water-Triggered Chemo- and Regioselective Synthesis of Fused Tricyclic XanthinesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Deju Ye Abstract A simple, convenient and green synthetic approach to diverse fused tricyclic xanthines has been developed via gold(I) complex-catalyzed intramolecular hydroamination or silver(I)-catalyzed isomerization-hydroamination of terminal alkynes under microwave irradiation in water. The first synthesis of N9-annelated xanthines has also been reported. [source] Reusable Gold(I) Catalysts with Unique Regioselectivity for Intermolecular Hydroamination of AlkynesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Antonio Leyva Abstract Two gold(I) phosphine complexes bearing the low-coordinating bis(trifluoromethanesulfonyl)imidate ligand, namely AuSPhosNTf2 and AuPPh3NTf2, are active catalysts for the regioselective intermolecular hydroamination of both internal and terminal alkynes under mild reaction conditions. The catalysts show a regioselectivity based on electronic rather than steric factors, which allow the preferential synthesis of regioisomers opposite to those described previously. This subtle chemo- and regioselectivity depends on the catalyst, substrates and reaction conditions employed, and allows one to perform new tandem reactions. These gold(I) complexes operate under free-solvent conditions, without exclusion of air, without addition of acidic promoters and can be quantitatively recovered and reused by simple precipitation in hexane. [source] Room Temperature Lewis Base-Catalyzed Alumination of Terminal AlkynesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009Yuhan Zhou Abstract An efficient and mild access to mixed dimethylalkynylaluminum reagents has been developed via a direct Lewis base-catalyzed alumination of terminal alkynes by trimethylaluminum. The use of bis(trimethylsilyl)methylamine enables the metalation at room temperature with only 1% of catalyst loading. [source] Copper-Catalyzed Efficient Multicomponent Reaction: Synthesis of Benzoxazoline-Amidine DerivativesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009Yongjia Shang Abstract We have developed an efficient copper-catalyzed method for the synthesis of the benzoxazoline-amidine derivatives. The protocol uses inexpensive copper(I) iodide as the catalyst, and furnished the expected product in good to excellent yields by a three-component reaction of sulfonyl azides, terminal alkynes and Schiffs' bases in terahydrofuran (THF) at room temperature for 8,h in the presence of triethylamine. This novel synthetic protocol is selective, efficient and general. A plausible mechanism for this process is proposed. [source] Synthesis of (E)-3-Alkylidene-1-pyrrolines by the Rhodium- Catalyzed Cyclization of Terminal Alkynes with Homopropargylic AminesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Yoshiya Fukumoto Abstract The cyclization of terminal alkynes with homopropargylic amines in the presence of a rhodium complex as catalyst leads to the formation of (E)-3-alkylidene-1-pyrrolines. The reaction tolerates a wide range of functional groups on the terminal alkynes. The formation of a vinylidene-rhodium complex, followed by the intermolecular nucleophilic attack of a homopropargylic amine nitrogen on the ,-carbon atom of the vinylidene-rhodium complex, is proposed as a key step in the catalytic reaction. [source] Immobilization of Porphyrinatocopper Nanoparticles onto Activated Multi-Walled Carbon Nanotubes and a Study of its Catalytic Activity as an Efficient Heterogeneous Catalyst for a Click Approach to the Three-Component Synthesis of 1,2,3-Triazoles in WaterADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Hashem Sharghi Abstract An efficient, regioselective, one-pot and two-step synthesis of ,-hydroxy 1,4-disubstituted 1,2,3-triazoles from a wide range of non-activated terminal alkynes and epoxides and sodium azide by way of a three-component click reaction using a catalytic amount of [meso -tetrakis(o -chlorophenyl)porphyrinato]copper(II) (5,mol%) in excellent isolated yields is described. The reactions were performed in water as a green solvent at ambient temperature without any additives. By performing two reaction steps in one pot and purifying only at the final step, this procedure excludes any interim purification of in situ generated organic azide intermediates, which significantly improves the overall yield and reduces the reaction time. To benefit from the recovery and reuse of the catalyst, a new heterogeneous catalyst was prepared by simple and successful impregnation of the catalyst onto activated multi-walled carbon nanotubes (AMWCNT). The heterogeneous catalyst was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic forced microscopy (AFM), and thermogravimetric (TG) analysis to estimate the amount of nitrogen adsorption, and Raman and FT-IR spectroscopy. Leaching experiments after ten successive cycles showed that the catalyst is most strongly anchored to the AMWCNT support. Mechanistically, porphyrinatocopper catalyzes each step of the reaction in different ways as a bifunctional catalyst including epoxide ring opening by azide delivery to epoxide, forming in situ generated 2-azido alcohols followed by activation of the CC triple bond of the starting terminal alkynes by forming a porphyrinatocopper-acetylide intermediate and thereby promoting the [3+2]-cycloaddition reaction as the key step to form the triazole framework. [source] Samarium Powder-Catalyzed Palladium-Free and Ligand-Free Sonogashira Coupling ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Jincheng Mao Abstract A study of samarium powder-catalyzed cross-coupling reactions of aryl halides with terminal alkynes is described. The couplings performed in the polyethylene glycol PEG-600 provided the corresponding coupling products in good yields. The first example of palladium-free, copper-free and amine-free catalytic system for Sonogashira couplings is presented in the absence of ligand. [source] Copper-Catalyzed One-Pot Synthesis of 2-Alkylidene-1,2,3,4- tetrahydropyrimidinesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Wei Lu Abstract A one-pot synthesis of N -sulfonyl-2-alkylidene-1,2,3,4-tetrahydropyrimidines via a highly selective and copper-catalyzed multicomponent reaction of sulfonyl azides, terminal alkynes and ,,,-unsaturated imines has been developed. The ,,,-unsaturated imine substrates could be generated from amines and ,,,-unsaturated aldehydes in a one-pot process. The procedure is concise, general and efficient. [source] Catalytic 1,2-Dicyanation of Alkynes by Palladium(II) under Aerobic ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Shigeru Arai Abstract A stereoselective 1,2-dicyanation of various alkynes in the presence of trimethylsilyl cyanide (TMSCN) by palladium(II) catalysis under aerobic conditions is investigated. This reaction includes two cyanation pathways, syn - and anti -cyanopalladation to alkynes that are activated by Pd(II). High syn -selectivity was observed in the reaction using terminal alkynes that have bulky substituents at a propargyl position and aliphatic internal alkynes. Furthermore, a dramatic acceleration was observed with substrates having an N -arenesulfonyl functionality at a propargyl position, this indicates that both sulfoxide and carbon-carbon triple bond act as Lewis bases to Pd(II). [source] | |||||||||||||||||||||||||