Presence Of CuCl Research Articles

Die Reaktion von 1‐Halogeno‐1‐Lithiocyclopropanen mit CuCl2: Konkurrenz zwischen ‘Carben‐Dimerisierung’ und oxidativer Kupplung

The Reaction of 1‐Halogeno‐1‐lithiocyclopropanes with CuCl2: Competition between ‘Carbene Dimerization’ and Oxidative CouplingThe 1‐chloro‐1‐lithiocyclopropanes 2a–d react at low temperature with CuCl2 to give diastereoisomeric mixtures of oxidative‐coupling products 5a–d and of ‘carbene dimers’ 6a–d. The relative amount of 5a–d increases with CuCl2 concentration and reaction time. Diastereoselectivity of the reaction seems to be low, and separation as well as spectroscopic structure assignment of single diastereoselectivity of the reaction seems to be low, and separation as well as spectroscopic structure assignment of single diastereoisomers are difficult. The conformational behavior of 1,1′‐dichloro‐1,1′‐bi(cyclopropyls) 5c and 5d is discussed. Contrary to 2a–d, 1‐bromo‐1‐lithiocyclopropanes normally react with CuCl2 to give ‘carbene dimers’ 6 and no coupling products 5. So far the only exception is 1‐bromo‐1‐lithio‐2‐phenylcyclopropane 2e which in the presence of CuCl2 gives some percents of coupling products 5e besides carbene dimers 6b as main products. An X‐ray structure analysis of the predominant diastereoisomer 5e was performed.

Two-step oxidative one pot functionalization of 2-benzylidene-1-tetralone in the PdII/CuII/Na2CO3-MeOH system: a novel route to 2-(?-methoxy)benzyl-1,4-naphthoquinone

A novel two-step oxidative one pot functionalization of 2-benzylidene-1-tetralone by its reaction with Na2PdCl4 in the presence of CuCl2 and Na2CO3 (in 1 ∶ 1 ∶ 2 ∶ 5 molar ratio) in MeOH was discovered. The reaction yields 2-(α-methoxy)benzyl-1,4-naphthoquinone.

Synthesis of dl-α-Tocopherol by Cross Coupling Reaction of Ene-type Chloride with the C10-Grignard Reagent

Ene-type chloride (5 a) was prepared with trichloroisocyanuric acid as a chlorination reagent from pentenylchromanol (3), obtained from myrcene and 2, 3, 5-trimethylhydroquinone in 3 steps. Chloride (5 a) reacted with 3, 7-dimethyloctylmagnesium bromide in the presence of CuCl (I) as the catalyst in THE to afford mixture consisting of SN2' type cross coupling products (7 a) and (8 a) with high regioselectivity. Compounds (5 b-e) reacted with the Grignard reagent in the presence of CuCl (I) to give SN2' type cross coupling products (7) and (8) with high regioselectivity Table-1. dl-α-Tocopherol was prepared in good yields by the hydrogenation of compounds (7 a) and (8 a).

N-tert-Butylglyoxylsäureamid als neues Reagens zur Peptid-Segmentverknüpfung via Vierkomponenten-Reaktion (4CR) / N-tert-Butylglyoxylicamide, the New Reagent for Peptide Segment Coupling by Four-Component Reaction

In contrast to the use of other aldehyd components, the Tetra Component Reactions (4CR) of carboxyl acids and primary amines with combinations of N-tert-butylglyoxylicamide and isocyanides produce carbonamides that yield the desired stereochemically uniform condensation products. Often a further advantage of such products is their possibility of being oxidized selectively in the presence of CuCl2 ·2H2O/NEt3/air (containing O2) into the carbonamides of the here used carboxyl acids and primary amines. In particular, such products can thus be converted selectively into α-acylamino and peptide derivatives. In case of the modelpeptide phenylaceticbenzylamide 8a quantitative cleavage yields, in the course of the appropriate dipeptide derivatives (8b-8f) cleavage yields of 56-81% are obtained.

Palladium catalyzed cyclization-carbonylation of allylic 2-alkynoates: Facile synthesis of α-alkylidene-γ-butyrolactone β-acetic acid derivatives

α-(Z)- and (E)- Chloroalkylidene-γ-butyrolactone β-acetic acid derivatives were prepared from easily available acyclic allylic 2-alkynoates using Pd 2(dba) 3 CHCl 3 as catalyst under 1 atm of CO in the presence of CuCl 2 and LiCl in high stereoselectivity.

A New Synthesis of γ-ButyrolactonesviaPalladium(II)-Catalyzed Cyclization of Trimethylsilylalkynes

In the presence of CuCl2 and O2, palladium(II)-catalyzed cyclization of 1-substituted 4-(trimethylsilyl)-3-butyn-1-ols produced γ-butyrolactones in satisfactory yields (50-74%). The effect of experimental parameters on the yield and on the reaction time has been studied. The best results were obtained by using Pd(OAc)2 or PdClNO2(CH3CN)2 as catalysts and a mixture of CH3CN and 1N HCl as solvent.

Catalytic oxidation of homoallylalcohols to α-alkoxytetrahydrofurans by a Pd-Nitro complex and molecular oxygen

Various homoallylalcohols were highly regioselective oxidized with molecular oxygen at the terminal carbon to afford cyclic acetals (α-alkoxytetrahydrofurans) using PdNO 2Cl(CH 3CN) 2 as a catalyst in the presence of CuCl 2 and t-butanol or isopropanol.

On the relationship between the structures of Cu(II) complexes and the course of their thermal decomposition

Thermal decomposition of [Cu4O(Cl+Br)6(OPPh3)4], starts at temperatures about 200°C. The decomposition proceeds in several steps. The intermediate formed in the first decomposition step (weight loss 2–4%) is a new crystalline phase with slightly different structure but with preserved central unit Cu4O. The only crystalline phases found in the further decomposition products was CuBr in all cases when the bromine atoms were present, the presence of CuCl was only observed at the decomposition of the hexachlorocomplex.

Electrochemical Oxidation of Hydrosilanes. A Synthetic Approach to Halosilanes and Disilanes

Abstract Electrolytic oxidation of dimethylphenylsilane (1) in the presence of CuCl2 or CuCl afforded chlorodimethylphenylsilane in high yields ( >90%), while similar electrolysis of 1 in the presence of BF4− ions afforded fluorodimethylphenylsilane in 90% yield. 1,2-Diphenyltetramethyldisilane was obtained from 1 in 48% yield by the electrolysis with a Pt–Cu electrode system. A “paired” electrolysis of methyldiphenylsilane on the anode and chloromethyldiphenylsilane on the cathode afforded 1,2-dimethyltetraphenyldisilane in 64% yield.

Coordination Polymers of CuII with the Ligand Pyrazine-2,3,5,6-tetracarboxylic Acid

The ligand pyrazine-2,3,5,6-tetracarboxylic acid in the presence of CuCl2 and the buffers CH3CO2X/CH3CO2H, X = K+, Rb+, Cs+ and (CH3CO2)2Mg/CH3CO2H, forms two quite different types of coordination polymers. With the monovalent K+, Rb+, or Cs+ buffer an almost right-angled dimeric unit is formed which polymerizes to form a zig-zag polymer {Cs4[Cu2{pztc)22H2O]⋅9H2O}∞ (1). This 'dimerizes' about a center of symmetry to form a two-dimensional polymer sheet. With the divalent Mg2+ buffer a mononuclear unit polymerizes to form a quasi-linear polymer {Mg(H2O)6[Cu(pztc)2H2O]⋅2H2O}∞ (2). The X-ray crystal structures of 1 and 2 indicate that the Cu atom exists in two quite different coordination environments (NO3, square pyramidal for 1 and N2O2, square planar for 2) and that the Cu-N(pyrazine) bond distances are much longer than normal.

Electrocatalytic C-C Double Bond Cleavage Reaction of Styrene with Molecular Oxygen Mediated by CuCl2

Abstract The electrocatalytic oxidation of styrene with molecular oxygen in the presence of CuCl2 in an acetonitrile solution promotes C-C double bond cleavage reaction to form benzaldehyde. Continuous supply of Cl− is required to keep the catalytic activity.

Heteronuclear complexes of platinum(II) and copper(I) bridged by alkynyl ligands

Reactions of cis-[PtCl2(PMe2Ph)2] with terminal alkynes RC2H (R = Ph or But) and diethylamine in the presence of CuCl (up to 0.35 mol per mol Pt) yielded the complexes cis-[PtCuCl(C2R)2(PMe2Ph)2]. The crystal structure for R = But showed that both alkynyl ligands are σ bonded to Pt and η2 co-ordinated to the Cu which has an approximately trigonal-planar geometry. The Pt(C2R)2CuCl system is distorted from planarity. Similar reactions, but with more CuCl (1 mol per mol Pt), led to trans-[PtCu2Cl2(C2R)2(PMe2Ph)2](R = But). Treatment of the compound [Pt(C2Ph)2(dppe)](dppe = Ph2PCH2CH2PPh2) with [Cu(MeCN)4][BF4] gave [PtCu(MeCN)(C2Ph)2(dppe)][BF4] which is believed to be structurally analogous to the neutral chloro complex. An acetone–acetonitrile solution of this complex deposited crystals of [Pt2Cu(C2Ph)4(dppe)2][BF4]. The crystal structure of the latter contains orthogonal platinum co-ordination planes and each of the four alkynyl ligands is η2 co-ordinated to a Cu atom in an approximately tetrahedral environment involving only carbon.

The influence of the polar headgroups of acidic diacetylenic phospholipids on tubule formation, microstructure morphology and Langmuir film behavior

The effect of modification of the polar headgroup of diacetylenic phospholipids on bilayer morphology and monolayer properties has been investigated. The lipids were prepared by substituting the choline portion of 1,2-bis(10, 12-tricosadiynoyl)-sn-glycero-3-phosphocholine with the glycols HO(CH 2) n OH ( n = 2, 3, 4), by means of a phospholipase D catalyzed transphosphatidylation. In the presence of CuCl 2 (pH 5.6 and ionic strength 0.18), the lipid with n = 2, produced a bimodal population of small diameter (0.1 μm) and large diameter (0.9 μm) tubules, the lipid for n = 3 produced a similar bimodal distribution of tubules except that the diameter of the smaller tubules increased to 0.3 μm. No small diameter tubules were formed from the lipid where n = 4. An increase or decrease either in the pH or ionic strength decreased the yield of tubules and affected the formation of the small diameter tubules, respectively. The counteranion of the metal salt present in the aqueous medium was also found to affect tubule diameter. The molecular area of the lipids was 70 A 2/molecule ( n = 2), 105 A 2/molecule ( n = 3) and 160 A 2/molecule ( n = 4). Monolayer studies suggested that the packing behavior of lipids at the air-water interface in the low surface pressure region was influenced by the subphase pH, ionic strength and counteranions.

Synthesis and purification of biologically active rat brain-derived neurotrophic factor from Escherichia coli

The cDNA for rat brain-derived neurotrophic factor was cloned as the prepro and mature sequences into two independent expression vectors under control of the T7 promoter. When these vectors were transfected into Escherichia coli the prepro and mature forms of brain-derived neurotrophic factor accounted for about 20% and 25% of total E. coli proteins, and displayed molecular sizes of 26 kDa and 15 kDa, respectively. Mature brain-derived neurotrophic factor was extracted from E. coli inclusion bodies, refolded in the presence of CuCl2 and purified. The resulting protein had an ED50 of 3 ng/ml in supporting survival of cultured embryonic dorsal root ganglion neurons.

The influence of anhydrous cupric chloride on the nature of the interactions between bromoform and 1,4-dioxane

Abstract Singh P.P. and Maken S., 1992. The influence of anhydrous cupric chloride on the nature of the interactions between bromoform and 1,4-dioxane. Fluid Phase Equilibria , 72: 299-308. Molar excess volumes, V e , and molar excess enthalpies, H e of 1,4-dioxane (D) saturated with anhydrous cupric chloride (S) (i.e. D which the complex D(S) in the liquid phase) + bromoform (BF) mixtures have been measured at 308.15 K. V e data have been analysed using the graph-theoretical model, and H E data using the ideal associated model (Hepler-Fenby) approaches. The analyses suggest that the presence of CuCl 2 in the mixture results in the formation of an associated complex, D(S), of S and D which interacts more strongly with BF than pure D. These conclusions have further been supported by NMR data of this mixture. The geometry of the D(S) and D(S) BF molecular entities have also been investigated.

Asymmetrische Katalysen, 73. Mitt. Enantioselektive Decarboxylierung von Methylphenylmalons�ure-Derivaten mit Cu(I)/Alkaloid-Katalysatoren

Methylphenylmalonic acid was decarboxylated to yield 2-phenylpropionic acid with an optical induction of 36% ee using catalytic amounts of CuCl and an excess of (+)-cinchonine in acetonitril. Methylphenylmalonic acid hemiethylester gave ethyl 2-phenylpropionate of 20% ee with catalytic amounts of CuCl and (+)-cinchonine, respectively. The tetraethylammonium salt of methylphenylmalonic acid could be decarboxylated in the presence of CuCl, (+)-cinchonine, and chiral carboxylic acids, the best result of 27% ee being obtained with malic acid.

Oxidation of 3-hydroxyflavones in the presence of copper(I) and copper(II) chlorides

The reactions of 3-hydroxyflavones with dioxygen in the presence of CuCl and CuCl 2 have been studied. 2-Benzoyl-2-hydroxy-3(2 H)-benzofuranone ( 2) was formed along with 2-hydroxybenzil ( 4), salicylic acid ( 5), benzoic acid ( 6), coumaronedione ( 8) and the depside ( 11). A copper(II) flavonolate complex has been also isolated.

Synthesis of fluorinated acetylenic ketones

A method of synthesis of fluorinated alkoxyethynyl ketones is described, by acylation of terminal acetylenic compounds with fluoracyl chlorides in the presence of CuCl.

Base-specific binding of copper(II) to Z-DNA. The 1.3-A single crystal structure of d(m5CGUAm5CG) in the presence of CuCl2.

Base-specific binding of copper(II) to Z-DNA. The 1.3-A single crystal structure of d(m5CGUAm5CG) in the presence of CuCl2.

Covalent modification of guanine bases in double-stranded DNA. The 1.2-A Z-DNA structure of d(CGCGCG) in the presence of CuCl2.

Covalent modification of guanine bases in double-stranded DNA. The 1.2-A Z-DNA structure of d(CGCGCG) in the presence of CuCl2.