Variety Of Alkyl Research Articles

Synthesis and Characterization of Novel Multifunctional High-Tg Photorefractive Materials Obtained via Reactive Precursor Polymers

We describe the synthesis of a new class of high-Tg multifunctional photorefractive polymers. They were obtained by radical copolymerization of methyl vinyl isocyanate and various N-substituted maleimides. Hole transporting carbazole moieties were attached through a variety of alkyl and phenyl spacers to the imide positions of the maleimides. In a polymer analogous reaction the reactive isocyanate groups of the precursor polymers were reacted with different hydroxyalkyl-terminated nonlinear optical chromophores. Two azo chromophores including dispersed red-1 and one pyrazolone dye were used. The resulting materials have been characterized by means of GPC, DSC, and UV/vis spectroscopy. All materials are amorphous and possess excellent solubility in common solvents such as chloroform and THF. Molecular weights range between 20 and 272 kg/mol. The glass-transition temperatures vary between 60 and 194 °C, depending on the length and the nature of the spacer groups between the maleimide rings and the carbazole...

Stereoselective elaboration of side chain residues in cyclopropane-containing dipeptide isosteres

A variety of alkyl, substituted alkyl, and aryl side chain residues in cyclopropane-containing dipeptide isosteres were introduced by the highly diastereoselective (dr ≥20:1) additions of transformed into the corresponding N-Boc-protected amines with little or no stereochemical erosion. organolithium or Grignard reagents to N, N-dimethylhydrazone 6. The resulting hydrazines were

Transition-Metal-Mediated Dihydropyran Syntheses.ExoSelective Hetero Diels−Alder Reactions of Cobaloxime Dienyl Complexes with Aldehydes

Cobaloxime 1,3-dienyl complex, 2-pyridine bis(dimethylglyoximato)cobalt(III)−(3E)-1,3-pentadiene, participates in exo selective hetero Diels−Alder reactions with a variety of alkyl and aryl aldehyd...

The synthesis of alkylated or acylated nitroarene cyclopentadienyliron complexes: an alternative approach to the synthesis of arylated alkanoates

Time-dependent oxidation of η6-alkylaniline-η5-cyclopentadienyliron hexafluorophosphates, 17–32, allows for the preparation of nitrobenzene complexes with alkyl 33–48 or keto 49 substituents. Alkylnitroarene complexes are prepared by the oxidation of their corresponding aniline complexes with H2O2 in CF3CO2H for 20 min. An increase in the reaction time to 24 h gives rise to nitroarene complexes with keto substituents in lower yields. The use of nitroarenes as starting materials in the synthesis of alkanoates is of importance since it allows for the preparation of a large number of this class of compounds with a variety of alkyl substituents. Two different approaches have been utilized to allow for the synthesis of alkanoates. The first approach involves nucleophilic aromatic substitution of alkylnitrobenzene complexes with ethyl alkylacetoacetates followed by demetallation to give the alkanoates. This methodology allows for the preparation of these esters with a variety of alkyl substituents in either the meta or para positions. Another route outlines the reaction of phenylsulfonylacetonitrile with nitroarene complexes to prepare alkanoic acid precursors with alkyl substituents in the ortho, meta and para positions. The preparation of a larger pool of nitroarene complexes clearly demonstrates the advantage of using the cyclopentadienyliron arene complexes in the synthesis of alkanoates or their precursors, arylated phenylsulfonylacetonitriles, over traditional synthetic routes.

Facile Electrophilic Iodination of Icosahedral Carboranes. Synthesis of Carborane Derivatives with Boron-Carbon Bonds via the Palladium-Catalyzed Reaction of Diiodocarboranes with Grignard Reagents

Electrophilic diiodination reactions of icosahedral closo1,2-C2B IOHI 2 and closo1,7-C2B IOHI 2 using 2 molar equiv of iodine monochloride in the presence of catalytic amounts of aluminum chloride yielded the corresponding clos0-9,12-12-1,2-C2B10H10 and closo-9,10-I2-1,7-C2B10H10 complexes in excellent yields. Palladium-mediated cross-coupling reactions of these diiodocarboranes with a variety of alkyl, aralkyl, and aryl Grignard reagents were reinvestigated, and it was demonstrated that the addition of copper(1) iodide as a cocatalyst is crucial to the success of this reaction. A reaction mechanism involving the initial formation of binary organocopper species (RCu; R = alkyl, aralkyl, aryl) followed by the reaction of (a-carborany1)palladium iodides (LzPd(Cb1)I and L2Pd(CbR)I; L = PPh3, Cb = c~oso-~ ,~ -C~BIOHIO, closo-1 7-C2BloHlo) via a four-centered transition state is proposed. The molecular structures of closo-9,10-12-1,7-C2B10H10, 1, and C~O~O-~,~~-(C~H~)~-~,~-C~BIOHIO, 10, have been determined. Crystallographic data are as follows: for 1, monoclinic, space group P21lc, a = 13.2719-

Novel thiophene-based macrocycles related to azacrown ethers

A range of compounds containing two 3-oxygenated thiophene rings linked through the oxygen atoms by a variety of alkyl and heteroalkyl chains has been prepared and subjected to electrophillic substitution, at C(2) and C(2′), giving, inter alia, bis-Mannich bases containing 14- to 22-membered rings; preliminary X-ray diffraction studies of representative metal complexes are in hand.

A simple convenient method for preparation of difluoromethyl ethers using fluorosulfonyldifluoroacetic acid as a difluorocarbene precursor

In the presence of catalytic amounts of sodium sulfate or cuprous iodide, a variety of alkyl and aryl difluoromethyl ethers were synthesized in moderate yields by the reaction of the corresponding alcohols and phenols with fluorosulfonyldifluoroacetic acid ( 1 ) in acetonitrile under mild conditions. Fluorosulfonyldifluoroacetate anion [FO 2SCF 2OC 2 -] ( 5 ) is believed to readily eliminate SO 2, CO 2 and F -, thus liberating CF 2:; insertion of difluorocarbene into O-H bonds and its capture by fluoride ion then result in the formation of ethers and by-product CF 3H, respectively.

ChemInform Abstract: A General Synthetic Route for Platinum Cluster Compounds Containing Carbonyl and Tertiary Phosphine Ligands and a Study of Their Reactions with Unsaturated Inorganic Molecules.

AbstractThe reduction of complexes such as (I) by zinc dust or NaBH4 in MeOH or acetone under a CO atmosphere is an efficient method for the formation of polynuclear complexes (II)‐(IV) which is superior in yield convenience and generality to other methods and applicable for compounds (I) containing tert. phosphine ligands with a variety of alkyl or aryl groups.

Deoxygenation of Sulpxoxides with Triethylpvosphite/Iodine/Nai

Abstract A variety of alkyl and aryl sulphoxides have been successfully deoxygenated under mild condition with triethylphosphite/Iodine/Sodium Iodide in good yields.

A general synthetic route for platinum cluster compounds containing carbonyl and tertiary phosphine ligands and a study of their reactions with unsaturated inorganic molecules

The reduction of cis-[PtCl2(CO)(PR3)](R = a variety of alkyl or aryl groups) by zinc dust or sodium tetrahydroborate under a carbon monoxide atmosphere is an efficient high-yield method for the formation of tri-, tetra-, and penta-nuclear clusters, which is superior in yield, convenience, and generality to other methods. The nuclearity of the cluster formed appears to be the result of a subtle interplay between the steric and electronic properties of the phosphine and, in the case of triphenylphosphine at least, is altered by the presence of free ligand. Reactions of some of the above clusters with the unsaturated inorganic molecules SO2, CS2, and COS are reported. In some reactions the initial cluster framework is retained with concomitant complete or partial substitution of the bridging carbonyl ligands but in other cases either cluster aggregation or degradation is observed.

Serum cholinesterase inhibition by boronic acid

Horse serum cholinesterase (acylcholine acylhydrolase, EC 3.1.1.8) was reversibly inhibited by a variety of alkyl- and areneboronic acids with K i values ranging from 6.2 mM (methaneboronic acid) to 3.1 μM (diphenylboric acid). Binding to the enzyme was apparently at the active center, because inhibition obeyed competitive kinetics and because boronic acids protected the enzyme from inactivation by phenylmethane-sulfonyl fluoride. Boronic acids should prove useful in probing the active center of serum cholinesterase.

Synthesis and Biological Activities of the Antibiotic B 371 and its Analogs

AbstractThe synthesis of the title compound 1 is described as well as the syntheses of a series of structural analogs of type 4. The antimicrobial in vitro activity of these vinyl isocyanides, substituted in β‐position either by an indole derivative or by an aryl or 2‐thienyl group, was tested against Escherichia Coli, Bacillus subtilis, and Mucor muhei TÜ 284 (Table 1). Some of the compounds 4 display higher activity than the naturally occurring parent compound 1. — A variety of alkyl 2‐isocyanoacrylates of type 5 were included in the biological test. Some of them display exceptionally high antimicrobial activity (Table 2). Upon conversion of the isocyano group into the formamido group (4 → 6), the biological activity is lost.

Reaction of Mg(3s3p1P1) with a variety of alkyl C–H bonds: Identical initial MgH(X 2Σ+, v=0) rotational quantum state distributions

The initial distributions of rotational quantum states of MgH(X 2Σ+, v=0) produced in the reaction of electronically excited Mg(3s3p1P1) with a variety of hydrocarbons containing alkyl C–H bonds have been found to be identical within experimental error. The distribution is peaked at fairly low values of rotational angular momentum (N≂10). This is in stark contrast to the reaction of Mg(1P1) with H2, where very high rotational excitation is observed and has been ascribed to side-on attack of the H–H bond. It is proposed that Mg(1P1) attacks alkyl C–H bonds directly in a relatively narrow cone of angles around the C–H bond axis and that the strength or location of a particular C–H bond has little effect on the dynamical process. Possible reasons for the differences in H2 and hydrocarbon as reactants are discussed, and the hydrocarbon results are compared to those reported by Luntz and co-workers on the reactions of O(3P) and O(1D2) with alkyl C–H bonds.

Synthesis of substituted thiacrown ethersviaa bromoalkoxylation reaction

AbstractA variety of alkyl‐ or phenyl‐substituted thia‐crown ethers were prepared in two or three stepsviabromoalkoxylation reactions of olefins. Dialkyl‐ and phenyl‐substituted mono‐and dithia‐crown ethers were obtained as single compounds, whereas monoalkyl‐substituted derivatives were a mixture of two positional isomers reflecting the isomeric mixture formation in the bromoalkoxylation reaction.

Electronic absorption spectroscopic studies of enolimine-ketoamine equilibria in Schiff bases

The enolimine-ketoamine equilibria in a variety of alkyl and arylsalicylaldimines have been studied in 1,2-dichloroethane, methanol, ethanol,iso-propanol andt-butanol by electronic absorption spectroscopy. The equilibrium depends on the nature of the alcohol and the strength of hydrogen bond formed with the ketoamine. In arylsalicylaldimines, the equilibrium is sensitive to the nature of the substituents.

ChemInform Abstract: PREPARATION AND STRUCTURES OF RUTHENIUM(III) COMPLEXES CONTAINING TERTIARY ARSINES, TERTIARY PHOSPHINES, AND ISOCYANIDES

AbstractDie Darstellung des Monopyridin‐ Derivats (II) aus dem Diarsin‐methanol‐Ru(III)‐Komplex (I) in Pyridin gelingt durch Abbruch der Reaktion mit Petrolether.

Preparation and structures of ruthenium(III) complexes containing tertiary arsines, tertiary phosphines, and isocyanides

Preparation of the complexes [RuCl3(AsPh3)2(py)] and [RuCl3(PPh3)2(py)](py = pyridine) is described. The latter has been treated with a variety of alkyl and aryl isocyanides at room temperature to produce complexes of general formula [RuCl3(PPh3)(py)(CNR)]. Dipole-moment measurements on [RuCl3(AsPh3)2(py)] confirm that it possesses a mer arrangement of the chloride groups and a trans arrangement of the arsines. Similar measurements show [RuCl3(AsPh3)(bipy)](bipy = 2,2′-bipyridyl) and [RuCl3(AsPh3)(py)2] to possess a mer arrangement of chloride groups with the pyridine molecules cis to one another in the latter complex.

Synthesis and reactions of the 1H-imidazo[1,2-a]pyrrolo[3,2-e]pyridine system

The reactions of 6-amino-1H-pyrrolo[2,3-b]pyridines with α-halogenocarbonyl compounds yielded 1H-imidazo-[1,2-α]pyrrolo[3,2-e]pyridines with a variety of alkyl and aryl substitutents. These imidazopyrrolopyridines underwent ready electrophilic substitution at the 3-position; when the 3-position was blocked 8-substitution occurred.

Detection and identification of organic radicals produced in the low pressure silent electric discharge by an electron spin resonance spin trapping technique

A method is described whereby free radicals are produced in a low pressure silent electric discharge between glass surfaces and are simultaneously deposited with 2-methyl-2-nitrosopropane as a spin trap on a cold surface. The resulting deposit is warmed to room temperature and subjected to electron spin resonance examination. A variety of alkyl and other radicals were trapped with different reactants in the discharge tube.

Alkylated steroids. Part 1. 16α-Substituted 17α-methylpregnanes

The sequential reaction of 3β-acetoxypregna-5,16-dien-20-one (1) with methylmagnesium bromide and then methyl iodide has been examined in detail. The major product (85%) was 3β-hydroxy-16α,17α-dimethylpregn-5-en-20-one (2). Other products identified were 3β-hydroxy-16α-methylpregn-5-en-20-one (4); the 21-methyl derivatives [(5) and (10)] of (2) and (4); the 21-(1-hydroxy-1-methylethyl) derivative (11) of (2); and a trace of the 21,21-dimethyl derivative (12) of (2). The scope of the reaction with regard to the range of substituents that can be introduced at positions 16 and 17 has been established by preparing a series of 16α-substituted 17α-methylpregnenolones with a variety of alkyl, aryl, and aralkyl groups. Some of these have been converted into the corresponding 16α,17α-disubstituted progesterones.