Presence Of CuCl Research Articles

Reaction of CBrF 2–CBrF 2 with hydrazones of aromatic aldehydes : Novel efficient synthesis of fluorocontaining alkanes, alkenes and alkynes

An olefination of hydrazones of aromatic aldehydes by CBrF 2–CBrF 2 under copper catalysis was investigated. In situ prepared aldehydes hydrazones were converted to (3-bromo-2,2,3,3-tetrafluoropropyl)arenes by reaction with CBrF 2–CBrF 2 in the presence of CuCl. Subsequent elimination of HF by sodium hydroxide resulted in stereospecific formation of fluorocontaining alkenes. Elimination proceeds stereoselectively, only Z-isomers of alkenes are formed. Elimination of two molecules of HF from (3-bromo-2,2,3,3-tetrafluoropropyl)arenes by treatment with potassium tert-butoxide leads to formation of (bromodifluoromethyl)alkynes. As a result a simple and efficient transformation of aromatic aldehydes to range of various fluorinated alkanes, alkenes and alkynes was elaborated.

Effect of Lithium Chloride on Allylation of Zirconacyclopentadienes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A novel method for the synthesis of 4(3 H)-quinazolinones

Condensation of anthranilamide with aryl, alkyl or heteroaryl aldehydes in refluxing ethanol and the presence of CuCl 2 afforded the corresponding 2-substituted quinazolinones in excellent yields.

Efficient, copper-catalyzed, aerobic oxidation of primary alcohols.

An additive is the key to success: Catalytic amounts of N-methylimidazole are crucial for the aerobic oxidation of primary aliphatic alcohols in the presence of CuCl, 1,10-phenanthroline (phen), and di-tert-butyl azodicarboxylate (DBAD). This reaction, under neutral conditions, yields the aldehydes quantitatively and selectively without overoxidation to the carboxylic acids.

A structurally characterised ruthenium bis(pyrazolyl)borate benzylidene complex containing an agostic Ru⋯H–C interaction: synthesis and catalytic activity

A ruthenium bis(pyrazolyl)borate benzylidene has been synthesised. A single crystal X-ray diffraction study showed that the complex contained an agostic Ru⋯H–C interaction. The complex displayed catalytic activity for the ring closing metathesis of diethyl diallylmalonate in the presence of CuCl as a co-catalyst in refluxing toluene.

A Novel Direct Synthesis of (2,2‐Difluorovinyl)benzenes from Aromatic Aldehydes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

CuCl Nanocrystals in Monocrystalline NaCl Matrix

It is demonstrated that the growth of CuCl crystals in a single crystal of NaCl can be realized by the doping of the melted NaCl solution with copper. The absorption spectra in ambient exhibit peaks allotted to the excitonic transitions with a displacement towards great energies. The mean size of the crystallites is approximately 20 Å. From absorption spectra analysis, it was also shown that the heat treatments lead to an increase of the size of the CuCl particles. X-ray diffraction patterns demonstrate the good crystallinity of the matrix as well as the presence of CuCl in this matrix.

Chemical Route to the Capped RNAs

Eukaryotic and viral messenger RNAs contain a CAP structure that plays an important role in the initiation of translation and several other cellular processes that involve mRNAs. In this paper, we report a convenient chemical approach to the preparation of milligram quantities of short, capped RNA oligonucleotides, which overcomes some of the limitations of previous approaches. The method is based on the use of a reactive precursor, m7GppQ [P1‐7‐methylguanosine‐5′‐O‐yl, P2‐O‐8‐(5‐chloroquinolyl) pyrophosphate]. The precursor reacts smoothly with 5′‐phosphorylated unprotected short RNA in the presence of CuCl2 in organic media. The feasibility of this approach was demonstrated by the synthesis of the capped pentaribonucleotide m7GpppGpApCpU. The synthesized capped oligonucleotide was isolated and purified by reverse phase and ion exchange HPLC with a final yield of 37%. The structure of the m7GpppGpApCpU was confirmed by 31P NMR, mass‐spectrometry and enzymatic hydrolysis.

Reaction of Catalytic Olefination of Hydrazones with Polyhaloalkanes. Investigation of Alkene Formation Chemoselectivity.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Effect of lithium chloride on allylation of zirconacyclopentadienes

The effects of lithium chloride on the allylation of zirconacyclopentadienes with allylic halides in the presence of CuCl have been studied. It is found that mono-allylation products are formed predominantly in the absence of lithium chloride, while the presence of lithium chloride leads to the formation of di-allylation products.

A New Approach to the Synthesis of Dithienylethanediones and Dithienylacetylenes

1,2-Dithienylethanediones were synthesized by modified acylation of thiophene and its homologs in the presence of aluminum chloride and pyridine. The bishydrazones of the products were converted into dithienylacetylenes by oxidation with atmospheric oxygen in pyridine in the presence of CuCl.

Asymmetric Hydroesterification of Styrene Using Catalysts with Planar‐Chiral Ferrocene Oxazoline Ligands.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A novel direct synthesis of (2,2-difluorovinyl)benzenes from aromatic aldehydes

A novel catalytic approach to (2,2-difluorovinyl)benzenes has been developed. It was found that hydrazones of aromatic aldehydes generated in situ could be converted to the corresponding (2,2-difluorovinyl)benzenes by catalytic olefination reaction (COR) with dibromodifluoromethane in the presence of CuCl.

Novel Efficient Synthesis of Dibromoalkenes. A First Example of Catalytic Olefination of Aliphatic Carbonyl Compounds.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Living/controlled radical autopolymerization of styrene in the presence of CuCl2 and 2,2′‐bipyridine

AbstractThe bulk autopolymerization of styrene (St) was successfully conducted in the presence of CuCl2 and 2,2′‐bipyridine (bpy) at 110 and 130°C. We found that this polymerization was a living/controlled radical polymerization at a [St]0/[CuCl2]0/[bpy]0 ratio of 54:1:2.5. The resulting number‐average molecular weights linearly increased with conversion, and the polydispersity indices were very narrow (<1.5). The polymerization rate increased with temperature. Increasing the ratios (i.e., 129:1:2.5, 259:1:2.5, and 386:1:2.5) led to a decrease in the ability to control the autopolymerization of St, even uncontrolled polymerization (i.e., 643:1:2.5). The analysis of end groups by 1H‐NMR indicated that the spontaneous generation of radicals from St were generated by a Mayo‐type process, and this living/controlled radical polymerization might have underwent a reverse atom‐transfer radical polymerization process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1532–1538, 2003

Preparation of Selanyl-Substituted Conjugated Enynes by Copper-Catalysed Coupling Reaction of (E)-γ-Selanyl Vinylzirconocene with Acetylenic Bromide

A stereoselective synthesis of conjugated enynes containing allyl selenide unit is reported. Selanyl-substituted conjugated enynes were obtained by the coupling reaction of ( E)-γ-selanyl vinylzirconocene with acetylenic bromide in the presence of CuCl.

Catalytic Olefination of Carbonyl Compounds. Effect of the Structure of the Carbonyl Compound on the Reaction.

The mechanism of the novel reaction of catalytic olefination of carbonyl compounds was studied. The reaction involves the transformation of hydrazones of aromatic aldehydes and ketones into the corresponding dichloroalkenes and symmetrical azines by the treatment with carbon tetrachloride in the presence of CuCl as a catalyst. The stability of intermediate diazoalkanes is the main factor determining the direction of the reaction. In the case of sufficiently stable diazoalkanes, other products can be formed under the reaction conditions along with the products of catalytic olefination.

Synthesis of conformationally stable 1,8-diarylnaphthalenes: development of new photoluminescent sensors for ion-selective recognition.

Highly constrained 1,8-diarylnaphthalenes exhibiting stability to isomerization have been prepared utilizing two consecutive CuO-promoted Stille cross-couplings of 1,8-dibromonaphthalene and 4-alkyl-9-trimethylstannylacridines. Screening of Pd catalysts Pd(PPh(3))(4), PdCl(2)dppf, or Pd(2)(dba)(3)/t-Bu(3)P and bases such as Cy(2)NMe, t-BuOK, K(3)PO(4), and Cs(2)CO(3) in DME or DMF revealed superior results of Stille over Suzuki coupling with acridylboronic acids or pinacolate derivatives. The meso syn- and C(2)-symmetric anti-isomers of 1,8-bis(4,4'-dimethyl-9,9'-diacridyl)naphthalene, 2, and 1,8-bis(4,4'-diisopropyl-9,9'-diacridyl)naphthalene, 3, did not show any sign of syn/anti-interconversion after heating to 180 degrees C for 24 h. Using the Eyring equation, we calculated the Gibbs standard activation energy for isomerization, DeltaG degrees (), to be higher than 180 kJ/mol. PM3 calculations of 2 and 3 suggest a highly congested structure exhibiting two parallel acridyl moieties perpendicular to the naphthalene ring. UV and fluorescence spectroscopy studies of 2 and 3 revealed remarkable quantum yields of these blue and green light emitters. Fluorescence titration experiments with the syn-isomer of 2 showed highly efficient quenching by Cu(II) ions, whereas almost no quenching effects were observed with Cu(I) and Zn(II) salts. The striking difference in fluorescence quenching was attributed to significant photoinduced electron transfer, resulting in nonradiative relaxation of excited Cu(II)-syn-2. Stern-Völmer plots of syn-2 in the presence of CuCl(2) showed a sigmoidal quenching curve indicating cooperative recognition, whereas a linear response was observed with CuCl and ZnCl(2). Fluorescence experiments in the presence of various amounts of CuCl, CuBr, and Cu(ACN)(4)BF(4) proved that the quenching is cation selective and independent of the nature of counteranions.

Asymmetric hydroesterification of styrene using catalysts with planar-chiral ferrocene oxazoline ligands

Chiral P, N-ferrocene ligands, 1-diphenylphosphino-1′-[( S)-4-isopropyl-2.5-oxazolinyl]-2′-( S p )-(trimethylsilyl)-ferrocene and its diastereomer, and 1-diphenylphosphino-1′-[( S)-4-isopropyl-2.5-oxazolinyl]-2′( S p )-(diphenylphosphino)-ferrocene and its diastereomer were used in the palladium-catalyzed asymmetric hydroesterification of styrene. The role of these ligands, which contain central, axial, and planar chirality, on the stereochemical outcome was investigated. A significant effect of using CuCl 2 as a co-catalyst on the reaction was observed. Excellent regioselectivity (b/n >99:1) with low ee (28%) was obtained in the presence of CuCl 2; moderate enantioselectivity (64% ee) but low regioselectivity (b/n, 40/60) was obtained in the absence of CuCl 2.

Palladium‐Catalyzed Intramolecular Oxidative Alkylation of Unactivated Olefins.

AbstractFor Abstract see ChemInform Abstract in Full Text.