Efficient Coupling Reaction Research Articles

Ligand-free copper(Ι)-catalyzed Sonogashira-type coupling of arylboronic acids with terminal alkynes

An efficient ligand-free CuI-catalyzed Sonogashira-type coupling reaction of arylboronic acids with terminal alkynes under air is described. The electron-deficient alkynes gave the desired cross-coupling products in good yields. Thus, it represents a simple and alternative method for the traditional Sonogashira reaction.

Step-growth polymerization and ‘click’ chemistry: The oldest polymers rejuvenated

Since its discovery in 2001, copper catalyzed azide–alkyne ‘click’ chemistry has been extensively used in polymer chemistry to modify polymeric materials and create advanced polymer structures by efficient coupling reactions. Surprisingly, the contribution of this Huisgen cycloaddition reaction to industrially important commodity polymers, prepared by step-growth polymerization, was not existing until recently. Nevertheless, since many decades academic and industrial research was focused on finding attractive synthetic pathways to introduce large contents of different reactive functional groups in several polymer classes such as polyesters and polyurethanes. Because of the high tolerance of azide–alkyne coupling reactions to a wide variety of functional groups and to extreme reaction conditions often used in step-growth polymerizations, the straightforward synthesis of alkyne-containing building blocks created an ideal platform to modify and broaden the physico-chemical properties of step-growth polymers by choosing readily available low and high molecular weight azide components. This feature article provides a comprehensive review covering the strategies toward ‘click’-functionalization of several classes of industrially important step-growth polymers.

A Simple Access to Symmetric Diarylamines via Copper(II)-catalyzed Coupling of Aqueous Ammonia with Arylboronic Acids

Abstract A simple and efficient CuII-catalyzed coupling reaction of arylboronic acids with aqueous ammonia under air is described. The reaction was conducted under atmospheric pressure and no additional ligand was required. Benzoic acid was added to tune the basicity of the reaction system.

A Versatile Synthesis of Electroactive Stilbenoprismands for Effective Binding of Metal Cations

A versatile synthesis of a new class of polyaromatic receptors (stilbenoprismands) containing a Delta-shaped cavity similar to that of the pi-prismand together with an intimately coupled electroactive stilbenoid moiety was accomplished via an efficient intramolecular McMurry coupling reaction. The presence of the Delta-shaped cavity in stilbenoprismands allows an efficient binding of a single silver cation as probed by (1)H NMR spectroscopy. Electron-rich stilbenoprismands undergo a ready oxidation to their highly robust cation-radical and dicationic salts. X-ray structure determination of a representative dicationic stilbenoprismand showed that the charges were largely localized on the tetraarylethylene moiety, which results in a twisting of the ethylenic C=C bond by approximately 35 degrees. Moreover, the electronic coupling among the stilbenoid and pi-prismand moieties in various stilbenoprismands was briefly probed by optical methods.

Copper(I) Halide Catalyzed Three-Component Coupling Reaction of Aldehyde, Pyrrolidine and Stannyl- and Silylacetylene

An efficient three-component coupling reaction of aldehyde, pyrrolidine and tributylstannylacetylene or triphenylsilylacety-lene to generate propargylamines has been developed by using copper(I) halides as promoters.

Efficient palladium-catalyzed coupling reactions of aryl bromides and chlorides with phenols

A convenient and general palladium-catalyzed coupling reaction of aryl bromides and chlorides with phenols was developed. Various functional groups such as nitriles, aldehydes, ketones and esters are well tolerated and the corresponding products are obtained in good to excellent yield.

Expanding the role of chemistry to produce new amphiphilic polymer (co)networks

Preparation of model amphiphilic polymer networks (APNs) using various polymerization mechanisms and/or organic coupling reactions are reviewed. A particular emphasis is made on controlled/“living” polymerization techniques in their diversities and how they impact on the structure-reactivity relationships. Advantages and limitations of each technique, as well as improvement of final physical/dynamical properties, are thoroughly discussed and compared for some of the mechanisms. Confrontation of experimental data with Flory’s theory is also displayed in the particular case of controlled radical polymerization (CRPs) techniques. Synthesis of model APNs by the end-linking process using efficient organic coupling reactions such as Michael-type addition, Huisgen 1,3-dipolar cycloaddition and thiol-ene click reactions are deeply illustrated and discussed.

Total synthesis of a xylo-Puromycin analog

N(6)-bis-demethylated xylo-Puromycin analog 2 was synthesized in 56% over 6 steps from adenosine 3, involving a Mattocks bromo acetylation, a regio- and stereo-selective ribo-epoxide ring opening with sodium azide and an efficient Staudinger-Vilarrasa coupling reaction for which the conditions have been optimized.

Palladium-catalyzed regiocontrolled internal heteroarylation of electron-rich olefins with heteroaryl halides

A highly efficient palladium-catalyzed Heck coupling reaction of heteroaryl halides with electron-rich vinyl ether and hydroxyalkyl vinyl ethers is described. It was found that the choice of solvent, ligand, and reaction temperature had a fundamental influence on the regioselectivity and reactivity of the reaction, and the combination of Pd(OAc)2 and DPPF in ethylene glycol led to the most effective catalytic system. Under these conditions, a variety of heteroaryl halides reacted very quickly with electron-rich olefins to afford exclusively the branched products in good to excellent yields without employing triflates, halide scavengers, or ionic liquids.

Polymer-supported palladium perfluorooctanesulfonate [Pd(OPf) 2]: A recyclable and ligand-free palladium catalyst for copper-free Sonogashira coupling reaction in water under aerobic conditions

Amberlyst A-21, a kind of well-known and cheap polymeric material, was treated with palladium perfluorooctanesulfonate [Pd(OPf) 2] giving a reagent with a palladium loading of 1.94 (wt%). The polymer-supported fluorous palladium catalyzes the highly efficient Sonogashira coupling reaction in water. The reactions can be performed under copper- and ligand-free conditions in an air atmosphere. The palladium catalyst is easily separated and can be reused several times without a significant loss of catalytic activity.

Copper-Catalyzed Alkyne−Aryne and Alkyne−Alkene−Aryne Coupling Reactions

The efficient copper-catalyzed two-component coupling reaction of alkynes with arynes and the three-component coupling reaction of alkynes with allylic chlorides and arynes have been developed. Copper acetylide was postulated as a transient intermediate for the initiation of the coupling reactions.

Synthesis of Non‐Natural Aromatic α‐Amino Acids by a Heck Reaction

AbstractAlkene 3, a TBS‐ and Cbz‐protected derivative of vinylglycinol, safely available from methionine, undergoes efficient Heck coupling reactions in high yields. The resulting products can be converted into enantiopure α‐amino acids with aromatic and heteroaromatic side‐chains. Compound 6a, a brightly fluorescent Fmoc‐protected pyrene amino acid is of special interest. Tripeptide 8a, composed of this building block and two arginines, binds to TAR, an RNA element regulating transcriptional efficiency in HIV, with a Kd value of 50 nM. This compound also inhibits a coupled cell‐free transcription‐translation assay (IC50 = 40 μM) and shows pronounced antibacterial activity against B. subtilis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Practical Synthesis of a Peptide Deformylase (PDF) Inhibitor

A practical chromatography-free synthesis of an N-formylated hydroxylamine peptide deformylase inhibitor LCD320 is described. A diastereoselective Michael reaction of (4S)-3-[2-(cyclobutylmethyl)-1-oxo-2-propenyl]-4-(phenylmethyl)-2-oxazolidinone with O-benzyl hydroxylamine was used to establish the key stereogenic center. We found that traces of residual Li+ from a previous step had a great impact on the diastereoselectivity of this reaction. A very efficient amidation coupling reaction of proline derivative (2S,4R)-4-fluoro-1,2-pyrrolidinedicarboxylic acid 1,1-dimethylethyl ester with weakly nucleophilic 3-pyridazinamine using methanesulfonyl chloride in the presence of 1-methylimidazole in DMF was also developed that proceeded without racemization.

Reusable, Polymer‐Supported, Palladium‐Catalyzed, Atom‐ Efficient Coupling Reaction of Aryl Halides with Sodium Tetraphenylborate in Water by Focused Microwave Irradiation

AbstractA rapid and efficient cross‐coupling reaction of sodium tetraphenylborate with aryl bromides was carried out in water at 120 °C in the presence of a polymer‐supported palladium catalyst and potassium carbonate under focused microwave irradiation. All four phenyl groups of sodium tetraphenylborate participated in the reaction and produced polyfunctional biaryls in excellent yields. The polymeric catalyst can be easily separated from the reaction mixture and reused more than 10 times without showing any decrease in activity.

Yb(OTf) 3-catalyzed propargylation and allenylation of 1,3-dicarbonyl derivatives with propargylic alcohols: one-pot synthesis of multi-substituted furocoumarin

A highly efficient and mild Lewis acid-catalyzed coupling reaction of 1,3-dicarbonyl compounds with propargylic alcohols has been established. Selective propargylation or allenylation products are obtained depending on the nature of propargylic alcohols. In addition, catalytic quantities of Yb(OTf) 3 can also effectively promote the propargylation and allylation of 4-hydroxycoumarins at the 3-position. By applying this reaction as the key step, a multi-substituted furocoumarin can easily be synthesized in a one-pot procedure. The advantages of this method are broad scope, mild conditions, and easy handling since water is the only side product.

Heterogeneous Pd/C‐Catalyzed Ligand‐Free, Room‐Temperature Suzuki–Miyaura Coupling Reactions in Aqueous Media

A mild and efficient ligand-free Suzuki-Miyaura coupling reaction catalyzed by heterogeneous Pd/C was developed. Aryl bromides and triflates undergo the cross-coupling with aryl boronic acids in excellent yields without the presence of any additives in aqueous media at room temperature. Aryl vinyl boronic acids are also applicable to this coupling reaction and provide the trans-stilbene derivatives in high yields. The application of wet-type Pd/C to the coupling reaction was achieved without any loss of activity under aerobic conditions, and the reuse of Pd/C is feasible for a fifth run without significant loss of activity. Inductively coupled plasma (ICP) mass-spectrometric analysis of the filtrate from the reaction mixture of 4-bromonitrobenzene with phenylboronic acid demonstrated that the palladium metal hardly leached into the solution within the limits of the detector (<1 ppm), thus suggesting that the present Suzuki-Miyaura reaction proceeded by heterogeneous catalysis.

Triazole: the Keystone in Glycosylated Molecular Architectures Constructed by a Click Reaction

The copper(I)-catalyzed modern version of the Huisgen-type azide-alkyne cycloaddition to give a 1,4-disubstituted 1,2,3-triazole unit is introduced as a powerful ligation method for glycoconjugation. Owing to its high chemoselectivity and tolerance of a variety of reaction conditions, this highly atom-economic and efficient coupling reaction is especially useful for the effective construction of complex glycosylated structures such as clusters, dendrimers, polymers, peptides, and macrocycles. In all cases the triazole ring plays a key role by locking into position the various parts of these molecular architectures. The examples reported and briefly discussed in this short review highlight the use of this reaction in carbohydrate chemistry and pave the way to further developments and applications.

The Use of Calcium Carbide in One‐Pot Synthesis of Symmetric Diaryl Ethynes.

AbstractChemInform 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.

Synthesis of a Protected δ-Glyco-amino Acid Building Block for Incorporation into Peptide Chains

The synthesis of a suitably protected sugar amino acid (δ-glyco-amino acid) as a building block to be incorporated into the peptide chain (N-terminus) of bioactive peptide analogues is described. Its efficient coupling reactions with pilot amino acids as well as dipeptides have been accomplished by standard peptide chemistry.

Three-Component Coupling Reactions of Thioformamides with Organolithium and Grignard Reagents Leading to Formation of Tertiary Amines and a Thiolating Agent

A highly efficient three-component coupling reaction between thioformamides and organolithium and Grignard reagents was developed. The generality of the process has been demonstrated by using various combinations of reactants and reagents. Information about the mechanism of the reaction has come from 1H and 13C NMR spectroscopic detection of the key intermediate. The LiS group in the intermediates generated by addition of the organolithium reagents to the thioformamides serves as a leaving group. The solid byproduct formed in these reactions, formulated as [LiSMgBr], can be used as a thiolating agent to transform acid chlorides into thioic acids and thioic acid anhydrides.