Efficient Oxidative Coupling Research Articles

Copper(i) iodide–DMAP catalyzed homo- and heterocoupling of terminal alkynes

A practical and efficient catalytic system comprising CuI and DMAP has been developed for the oxidative homo- and heterocoupling of terminal alkynes under aerobic conditions at room temperature. The catalytic utility of DMAP for efficient oxidative coupling of terminal alkynes has been explored. The CuI–DMAP catalytic system avoids the need for excess base and specialized ligands in oxidative coupling. Short reaction times make this approach economical and environmentally friendly.

An efficient oxidative coupling method for synthesis of novel diastereomeric biaryl diols derived from estrone

An efficient oxidative coupling of estrogen derivatives was developed. Several 2-substitutent-17-deoxyestrones were applied to the aerobic oxidative coupling reactions catalyzed by CuCl2/TMEDA. The products were obtained as diastereoisomers with moderate to good yields. As chiral ligands, three couples of diastereoisomers were applied to the asymmetric HDA reaction to investigate their chemical properties.

ChemInform Abstract: Efficient and Selective Multicomponent Oxidative Coupling of Two Different Aliphatic Primary Amines into Thioamides by Elemental Sulfur.

An efficient and selective multicomponent oxidative coupling of two different aliphatic primary amines into thioamides by elemental sulfur under solvent-free conditions has been developed.

Efficient and Selective Multicomponent Oxidative Coupling of Two Different Aliphatic Primary Amines into Thioamides by Elemental Sulfur

An efficient and selective multicomponent oxidative coupling of two different aliphatic primary amines into thioamides by elemental sulfur under solvent-free conditions has been developed.

An Efficient PIFA-Mediated Synthesis of a Directly Linked Zinc Chlorin Dimer via Regioselective Oxidative Coupling

The synthesis of a directly linked zinc chlorin dimer was first achieved by a facile and efficient oxidative coupling of zinc chlorin monomers with phenyliodine bis(trifluoroacetate) (PIFA). The reaction shows high regioselectivity at the 20-position near the hydrogenated pyrrole ring producing selective dichlorin in 74% yield.

A Novel Sodium Nitrite‐Catalyzed Oxidative Coupling for Constructing Polymethoxyphenanthrene Rings

AbstractAn efficient and green oxidative coupling for the direct construction of polymethoxyphenanthrene rings has been developed, which uses environment‐friendly sodium nitrite as catalyst and oxygen as terminal oxidant. This methodology also provides an alternative possibility for forming biaryl products.

Efficient oxidative coupling of 2,6-disubstituted phenol catalyzed by a dicopper(ii) complex

Complexation of a rigid multi-pyridine ligand bis(2-pyridyl)-1,8-naphthyridine (bpnp) with [Cu(2)(TFA)(4)] (TFA = trifluoroacetate) resulted in the formation of a dinuclear copper(II) complex, namely [Cu(2)(bpnp)(μ-OH)(TFA)(3)] (1). This complex has been characterized by X-ray crystallographic, spectroscopic and elemental analyses. Complex 1 is an efficient catalyst for the oxidative coupling of various 2,6-disubstituted phenols with molecular oxygen. Yields and selectivity depend on the reaction conditions employed, the best results being obtained in isopropanol or dioxane at 90 °C with yields of >99%. Mechanistic pathway of the catalysis is discussed.

A simple and efficient approach to the synthesis of 2-substituted benzimidazole via sp3 C–H functionalization

A facile and novel approach to the synthesis of 2-substituted benzimidazole was developed via a tandem reaction following sp3 C–H functionalization. Here we report a simple, efficient and tandem oxidative dehydrative coupling reaction of N-benzylbezene-1,2-diamine in the presence of oxidant tert-butyl hydroperoxide (TBHP) in solvent acetonitrile to give substituted benzimidazole.

Synthesis of N-(2-Pyridyl)indoles via Pd(II)-Catalyzed Oxidative Coupling

Readily available Pd(II) chloride catalysts can catalyze selective and efficient oxidative coupling between N-aryl-2-aminopyridines and internal alkynes to yield N-(2-pyridyl)indoles. This process involves the ortho C-H activation of N-aryl-2-aminopyridines, and CuCl(2) was used as an oxidant. Compared to our previously reported Rh(III)-catalyzed synthesis of this class of product, this method is advantageous with a wider scope of alkynes and cost-effective Pd(II) catalysts. Molecular oxygen can be used as a terminal oxidant.

Efficient oxidative coupling of amines to imines catalyzed by manganese(III) meso-tetraphenylporphyrin chloride under ambient conditions

Highly efficient oxidative coupling of amines to imines by tert-butyl hydroperoxide (t-BuOOH) in the presence of metalloporphyrins has been reported. Manganese porphyrin showed excellent activity and selectivity for the oxidative coupling of amines to imines under ambient conditions. Moreover, a plausible mechanism involving high valence oxo intermediate has been proposed.

ChemInform Abstract: Metal‐Free Air Oxidation of Thiols in Recyclable Ionic Liquid: A Simple and Efficient Method for the Synthesis of Disulfides.

AbstractThe efficient oxidative coupling procedure is applicable to a wide range of thiols including captopryl (III) and L‐cysteine (V).

ChemInform Abstract: A Simple and Efficient Oxidative Coupling of Aromatic Nuclei Mediated by Manganese Dioxide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Novel Conversion of Thiols into Disulfides, via S-Nitrosothiol Intermediates Using Trichloronitromethane.

Abstract An efficient oxidative coupling of thiols to give disulfides via thionitrite (S-nitrosothiol) intermediate is described using trichloronitromethane as an efficient reagent in organic solvents and water. Cysteine and glutathione are converted into the corresponding disulfides in water in high yields.

A Simple and Efficient Oxidative Coupling of Aromatic Nuclei Mediated by Manganese Dioxide

Oxidative intramolecular coupling of the aryl rings of various stilbenes for direct construction of the phenanthrene ring system is promoted efficiently by manganese dioxide―trifluoroacetic acid at room temperature in excellent yields. This approach is also applied to the intermolecular biaryl coupling of 2-naphthols, 2-naphthalenethiol, 2-naphthylamine, a phenol ether and a phenol under very mild conditions. An electron-transfer mechanism is proposed in which manganese dioxide acts as a two-electron oxidant.

Synthesis of Spiro Compounds through Tandem Oxidative Coupling and a Framework Rearrangement Reaction

A highly efficient oxidative coupling of 2-naphthols and a rearrangement tandem reaction to afford unique spiro compounds in the presence of FeCl(3).6H(2)O in up to 88% yield have been developed.

Highly efficient aerobic ruthenium-catalyzed oxidative cross-dehydrogenative coupling for sp3–sp3 carbon–carbon bond formation

A highly efficient sp3–sp3 carbon–carbon bond formation system was developed for the aerobic ruthenium-catalyzed oxidative cross-dehydrogenative coupling reaction between tertiary amines and sp3 C–H compounds in the presence of RuCl3/O2, thus giving the corresponding α-functionalized amines. Compared with the reported method, H2O2 or tBuOOH was replaced successfully by economical and facile oxygen as the oxidant. Three types of activated C–H bonds for pronucleophiles were evaluated in this system. All these features combined are in accordance with important prospective green chemistry aspects.

Viral Capsid DNA Aptamer Conjugates as Multivalent Cell-Targeting Vehicles

Nucleic acid aptamers offer significant potential as convenient and evolvable targeting groups for drug delivery. To attach them to the surface of a genome-free viral capsid carrier, an efficient oxidative coupling strategy has been developed. The method involves the periodate-mediated reaction of phenylene diamine substituted oligonucleotides with aniline groups installed on the outer surface of the capsid shells. Up to 60 DNA strands can be attached to each viral capsid with no apparent loss of base-pairing capabilities or protein stability. The ability of the capsids to bind specific cellular targets was demonstrated through the attachment of a 41-nucleotide sequence that targets a tyrosine kinase receptor on Jurkat T cells. After the installation of a fluorescent dye on the capsid interior, capsids bearing the cell-targeting sequence showed significant levels of binding to the cells relative to those of control samples. Colocalization experiments using confocal microscopy indicated that the capsids were endocytosed and trafficked to lysosomes for degradation. These observations suggest that aptamer-labeled capsids could be used for the targeted drug delivery of acid-labile prodrugs that would be preferentially released upon lysosomal acidification.

Efficient oxidative coupling polymerization for synthesis of thermosetting poly(phenylene ether) copolymer with a low dielectric loss

A novel oxidative coupling polymerization using a water/toluene heterogeneous system for the synthesis of thermosetting Poly(phenylene ether) copolymer (Allyl-PPE) was developed. Allyl-PPE with a narrow molecular weight distribution and a low copper content was obtained in the presence of a Cu/TMEDA catalyst dissolved in water droplets. This method solved the problems during the synthesis of the Allyl-PPE with conventional Cu/pyridine catalysts. The resulting Allyl-PPE exhibited excellent dielectric properties (ε′ = 2.4, tan δ = 0.002 at 10 GHz), and it will be useful for applications to high-speed and high-frequency printed circuit boards.

Dual activation in oxidative coupling of 2-naphthols catalyzed by chiral dinuclear vanadium complexes

An efficient enantioselective oxidative coupling of 2-naphthol derivatives based on a concept of dual activation catalysis is realized. A chiral dinuclear vanadium(IV) complex ( R a, S, S)- 1e possessing ( S)- tert-leucine moieties at the 3,3′-positions of the ( R)-binaphthyl skeleton was developed, which was found to promote the oxidative coupling of 2-naphthol to afford ( S)-BINOL with 91% ee. To verify the dual activation mechanism, mononuclear vanadium(IV) complex ( S)- 8 was also prepared. Kinetic analysis revealed that the reaction rate of oxidative coupling of 2-naphthol promoted by ( R a, S, S)- 1e is 48.3 times faster than that of ( S)- 8. The two vanadium metals in the chiral complex activate two molecules of 2-naphthol simultaneously in an intramolecular manner coupling reaction, achieving a high reaction rate with high enantiocontrol. Reaction mechanisms of the oxidative coupling reaction promoted by either vanadium(IV) or vanadium(V) complexes are also described.

An Efficient Waste-Free Oxidative Coupling via Regioselective C−H Bond Cleavage: Rh/Cu-Catalyzed Reaction of Benzoic Acids with Alkynes and Acrylates under Air

[structure: see text]. The direct oxidative coupling of benzoic acids with internal alkynes proceeds efficiently in the presence of a rhodium/copper catalyst system under air to afford the corresponding isocoumarin derivatives. The reaction forms no wastes except for water. Under similar conditions, the aerobic coupling with acrylates also takes place smoothly to produce 7-vinylphthalide derivatives via divinylation and subsequent cyclization.